A journalist has been shot dead in Derry in what police in Northern Ireland are treating as a "terrorist incident".

Assistant chief constable Mark Hamilton, from the Police Service of Northern Ireland, said a murder inquiry had been launched after the death.

Lyra McKee, 29,  was killed during rioting after police searches in Derry's Creggan area on Thursday night.  Petrol bombs were reportedly thrown at police Land Rovers.

Ms McKee was an editor for the news site Mediagazer and was based in Belfast, according to literary agency Janklow and Nesbit's website. Her work included examining the fallout of decades of violence in Northern Ireland, and she was described as a rising star of investigative journalism in an announcement of a publishing deal last year.

HeraldScotland:

Assistant Chief Constable Mark Hamilton told a press conference police believe the attack was carried out by "violent dissident republicans", adding: "Our assessment at this time would be that the New IRA is the most likely to be behind this and that forms our primary line of inquiry."

He said police had been carrying out a search operation in the Creggan area of Derry when a public order situation developed during which more than 50 petrol bombs were thrown at police and two cars hijacked and set on fire.

"Unfortunately, at 11pm last night, a gunman appeared and fired a number of shots towards police and a young woman, Lyra McKee, 29 years old, was wounded," she said.

READ MORE: Dissident republican group linked with four murders since 2011

"She was taken away in a police landrover to Altnagelvin Hospital but unfortunately she has died there. We have now launched a murder inquiry here in the city.

"We believe this to be a terrorist act, we believe it has been carried out by violent dissident republicans, our assessment at this time is that the new IRA are most likely to be the ones behind this and that forms our primary line of inquiry."

Mr Hamilton continued: "Can I say also, I want to pass my deepest sympathies to the family of Ms McKee, this is a horrendous act, it is unnecessary, it is uncalled for, it's totally unjustified.

"But not only is it a murder of a young woman, it is an attack again on the people of this city.

"I stood here in January and we talked about the bomb and the act of violence against this city, and yet again we see another act of violence in this city which has had horrendous consequences and which will affect people for many, many years.

"I would appeal to people, particularly this Easter weekend, to stay calm, I would appeal to people who are intent on violence to draw back, I would appeal to people with influence to use your influence and make sure this is peaceful weekend. Not only this weekend but going forward in this city.

"These acts of violence are bringing nothing to this city, all they are doing is bringing misery to one family, but also particularly to this city and also to our broader province."

It comes a month after the New IRA claimed responsibility for a number of package bombs posted to targets in London and Glasgow.

Devices were sent to Heathrow and London City airports, Waterloo station and the University of Glasgow.

Leader of the Ulster Unionist Party Robin Swann said news of the death was "devastating".

There are reports that the trouble broke out after police raids on houses in the Mulroy Park and Galliagh areas.

He tweeted: "A precious life lost, we can't go back to this nor can we allow others to drag us back."

Democratic Unionist Party leader Arlene Foster tweeted: "Heartbreaking news. A senseless act. A family has been torn apart.

"Those who brought guns onto our streets in the 70s, 80s & 90s were wrong. It is equally wrong in 2019.

"No one wants to go back. My thoughts are also with the brave officers who stood in defence of their community."

Mark H Durkan, SDLP MLA for Foyle, said he was "heartbroken and angry" by the killing.

"Just leaving Creggan, heartbroken and angry at the senseless loss of a young life," he tweeted.

"Violence only creates victims, that's all it ever has done. The thoughts and prayers of our city are with the young woman's family and friends, may she rest in peace."

The Northern Ireland Policing Board said the killing was "utterly shocking" and appealed for witnesses or anyone with information to contact the police or Crimestoppers.

Sinn Fein deputy leader Michelle O'Neill said the killing in Derry was a "senseless loss of life".

She said: "I am shocked and saddened at the tragic news that a young woman has been shot dead by so-called dissidents in the Creggan estate tonight.

"The murder of this young woman is a human tragedy for her family, but it is also an attack on all the people of this community, an attack on our peace process and an attack on the Good Friday Agreement.

"I unreservedly condemn those responsible for killing this young woman.

"We will remain resolute in our opposition to the pointless actions of these people who care nothing for the people of Derry.

"We remain united in our determination to building a better and peaceful future for all."

Ms O'Neill added: "Those responsible should listen to the people, they should disband immediately and end their pointless actions against the community which tonight has tragically claimed the life of a young woman.

"I am appealing for calm and I urge anyone with any information about this killing to bring it forward immediately to the police and assist their inquiries."