Most are young, mainly teenagers, who at times appear to be looking for a fight. Ski masks pulled over their faces and wielding clubs or iron bars, they patrol the barricades that mark the gateway to what has been dubbed the "People's Republic of Donetsk".
Kitted out in tracksuits and protective knee and arm pads, they cut a very different dash from their elderly pro-Russian grey-haired comrades and old communists who amble about wearing black caps and red star lapel badges.
Young and old, they have come to man the barricades, determined to continue their occupation of Donetsk's regional administration building that towers above Pushkin Boulevard in this eastern Ukrainian town.
"Russia come to us," go the words of a song blaring out from the loudspeakers on the steps outside the building behind three barricaded redoubts piled high with tyres, barbed wire and sandbags.
Every day on a stage next to these speakers in front of the headquarters' entrance there are renditions of patriotic Russian songs and poetry readings and the occasional impassioned warning against the evils of the west by volunteer speakers.
Sentiment here in Donetsk has always been pro-Moscow and reminders of the communist past are never far away. Walk around Donetsk's wide tree-lined streets and you will come across a Second World War tank sitting on a plinth as monument to those who fell in war against Nazi Germany.
Elsewhere, you might stumble upon a bust of "Iron" Felix Dzerzhinsky, founder of the Bolshevik secret police. The man who appointed him, Vladimir Ilyich Lenin, has a square that bears his name all to himself. "We do not want the USSR back, but we do not want someone telling us who are our friends and who are our enemies," was how Denis Pushilin, self-styled leader of the "People's Republic of Donetsk," summed up the position of the pro-Russian militants.
Pushilin has said he does not consider his forces to be bound by Russia's signature at the talks held in Geneva this week. Regarding Russian foreign minister Sergei Lavrov's participation in the agreement, he said: "Lavrov did not sign anything for us."
For Pushilin, his allies and supporters, their own demands are clear enough. They refuse to vacate the premises they have occupied until the new leaders in Kiev leave their government posts and a referendum is held no later than May 11 that would ask residents of the region to which country, Russia or Ukraine, do they want to belong.
All this of course has thrown a spanner in the works of the deal reached last Thursday in Geneva by Ukraine, Russia, the United States and the European Union aimed at pulling eastern Ukraine back from the brink of war.
That much was made clear by the pro-Russian activists I met over the last few days inside the Donetsk administration building.
Passing through the pat-down security search by gruff, threatening sentries, you enter a building festooned with banners and posters denouncing the US, EU and "fascists". Ideologically lost on the occupiers, of course, is the irony that various other banners emblazoned with the communist hammer and sickle motif and the face of Joseph Stalin also represent something of a dubious history.
In what was once the building's ground-floor foyer a makeshift kitchen is run by supporters - their stalls and tables laden with food and urns of steaming-hot coffee to feed the armed men that come and go.
Occasionally, inside the ransacked building, I was to catch glimpses of a few militants in flak jackets and camouflage uniforms carrying Kalashnikov assault rifles and radio handsets, but these apparently "professional" gunmen seem less visible since Thursday's Geneva deal and the Ukraine government's Easter suspension of what it has described as an anti-terrorist operation to oust pro-Russian occupiers from government premises.
Even before the Easter suspension of the operation, here in the centre of Donetsk this warning of a military operation sounded more like a catch-all phrase than any real call to action. The simple truth is that there is precious little evidence of pro-Russian activists being confronted by local police or Ukrainian army units. Only yesterday, I watched as police mingled with the crowd near the barricades outside the administration building.
"The police have 'post-Maidan syndrome'," was how local journalist Vitlay Sizov summed it up, referring to the protest movement that recently brought down Moscow-backed Ukrainian president Viktor Yanukovich after the uprising in Kiev.
Short of effective forces, Ukraine's government has shown little will to recapture the dozen or so town halls, police stations and other sites seized over the past two weeks.
Back inside the 11-storey Donetsk building, meanwhile, the situation can best be described as organised chaos. On the ground floor a makeshift pharmacy and triage centre full of medicines stands ready to deal with casualties that may occur from any attempt by Ukrainian government forces or the army to storm the building.
On one floor, as I paused to look at searing caricature posters of acting Ukrainian president Oleksandr Turchynov, presidential candidate Yulia Tymoshenko and US leader Barack Obama, a young activist in a black ski mask and carrying a baseball bat tapped me on the shoulder. "F*** Turchynov, F*** Tymoshenko," he announced, jabbing at the cartoon drawings with the bat and evidently grinning behind the mask he wore.
On the 11th floor, the chiefs of the "People's Republic of Donetsk," were keen to impart their observations about the current Ukrainian government and world leaders. "All the world is listening to some fascists from western Ukraine and Kiev but they don't listen to us," complained Pushilin at an impromptu press conference, designed to show defiance in the wake of the Geneva deal. "Thanks to the western Europeans and the world, the Russian bear has been awoken and we have suffered under Kiev's political ambitions for 25 years and we can do it no more," Pushilin continued, reiterating that they will stand fast in their occupation until all demands are met.
On Friday, Ukrainian prime minister Arseniy Yatsenyuk and Turchynov announced what they said was a sweeping constitutional-reform plan aimed at addressing many of the concerns of the pro-Russian activists.
The plans call for replacing appointed mayors and regional governors with officials elected locally and giving regional governments like that in Donetsk more say over how budgets are allocated and spent.
Under the plan, towns, cities and regions could also independently decide whether to make Russian an official language alongside Ukrainian - a thorny issue for the protestors here in Donetsk and elsewhere across the east of the country.
On the table too as part of the deal is an offer of amnesty for all those pro-Russian militants prepared to put down their weapons and leave the buildings they occupy but, so far, this seems to have fallen on deaf ears.
"It's our struggle for towns, cities and freedom," said 18-year-old Constantine as we spoke on the barricades. "We are normal people who struggle for our rights - not terrorists as the Kiev government say." Like so many activists here, Constantine wanted only his first name used. "I will not leave until we have what we want," he continued, his face blackened and grimy from the smoke of the brazier fires the activists use at night to keep themselves warm.
What if the Ukrainian army come with tanks and infantry I asked him? "Then we will fight and use these," he replied nodding in the direction of a crate of beer bottles converted into Molotov cocktails, their petrol-soaked rag fuses sticking from the bottle necks and giving off a powerful smell.
Yesterday, Pushilin, renewed his call for a referendum giving the eastern areas sovereign power to choose possible annexation.
But an opinion poll published by a Kiev institute found only about one third of people in the easternmost regions of Donetsk and Luhansk saying they would vote for rule by Moscow - although more than two thirds regard the new Kiev leadership as having illegally usurped the Kremlin-backed president in February.
Yesterday too Russian President Vladimir Putin held out the prospect of better relations with the west but made clear it would depend on concessions from his adversaries in the crisis over Ukraine.
"I think there is nothing that would hinder a normalisation and normal cooperation," he said in an interview broadcast by Russian state television in which he commented favourably on the appointment of a new head of Nato. "This does not depend on us. Or rather not only on us. This depends on our partners," insisted Putin.
For now Moscow continues to deny it has plans to invade, despite massing thousands of troops on the border. This weekend a Kremlin spokesman said troops on the border were there only as a precaution against any spillover of violence, not to interfere. Few here, however, doubt that such interference has already occurred and that Moscow has only quietly saved its hand for the moment. Right now the situation remains uncertain and conspiracy theories do the rounds here in Donetsk.
Time and again people I have spoken to on both sides of the divide have mentioned how they believe the rich and powerful of Ukraine may be fomenting unrest behind the scenes to further their own business interests and curry favour with Moscow.
"You need look no further than the tycoons - they are what is driving this," insisted one young women, who preferred not to be named, but summed up the suspicions of many here.
This weekend the barricades are still being made higher and stronger around Donetsk's administration building. More tyres, barbed wire and Molotov cocktail petrol bombs are being prepared.
Many in Donetsk fear that once the Easter holidays are over it will be back to the business of brinkmanship and it will only take the slightest spark to ignite a wider conflict. As a result, ambulances loaded with doctors and paramedics stand just yards from the barricades in readiness around the clock.
Yesterday, I asked a three-woman crew - Olga, Tatiana and Helena - what they thought the coming days and weeks would bring in Donetsk and other contested town and cities in eastern Ukraine?
"It will get much worse before it gets better," said the doctor, Helena, standing in the drizzle not far from some pumped-up activists wearing flak jackets and a motley assortment of paramilitary uniforms.
"These people are not occupiers, they are only wanting to live better," she added, indicating the she and her colleagues had certain sympathies with those holed up behind the barricades.
"No, it's not over yet, and these people will not give up," she insisted.