Part one: The airport attack
By Torcuil Crichton and Judith Duffy

Terror came to Scotland yesterday when an attempted car-bombing at Glasgow Airport caused widespread chaos and pushed Britain on to "critical alert" for further attacks. With Gordon Brown's premiership undergoing a baptism of fire, the prime minister called on the British people to be "united, resolute and strong" in the face of an imminent assault.

Last night, police confirmed that the incident north of the Border was being linked to the car bombs discovered in London the previous day.

In another development, it emerged that the Royal Alexandra Hospital in Paisley, where one suspect in the airport attack was taken, had to be partially evacuated after a "suspicious device" was found on his person. Police refused to confirm that it was a suicide belt.

Security at airports, ports and public events will immediately be tightened considerably while police frantically hunt for members of an Islamist terror cell assumed to be responsible for the London car bombs.

Two men were under arrest last night after a Jeep Cherokee 4x4 was driven into the entry doors of Glasgow Airport at 3.15pm, shaking the nation out of its complacency that British Islamist terrorism was a London phenomenon.

Having failed to breach the airport doors with the car, one of its occupants sprinkled petrol over himself and the vehicle, causing an explosion that set the front of the airport check-in area alight. Despite the horrific nature of the attack there were no reports of fatalities or serious injuries, with just one member of the public treated for a leg injury.

Strathclyde Police last night linked the Glasgow incident to the double car bombing attempt in London's Haymarket on Friday. However, Willie Rae, chief constable of Strathclyde Police, said there was no prior intelligence that Scotland was going to be attacked.

"There are clearly similarities and we can confirm that this is being treated as a terrorist incident," he added.

The Metropolitan Police have, by now, identified the London bombers from forensic and CCTV footage and consider the car drivers and their associates to be on the run and dangerous.

Last night, after the prime minister chaired the second meeting of the Cobra security committee in a day, the UK threat level was raised from "severe", where it has been from some time, to "critical", the highest level usually set when there is definite information on an imminent attack.

Security sources emphasised there was no specific intelligence pointing to an attack but that a series of three attempted car bombings could lead to further terrorist operations.

Eyewitnesses at the airport spoke of incredible scenes as one of the car occupants attempted to throw what appeared to be a petrol bomb into the passenger area after the car rammed the doors.

He emerged from the vehicle and collapsed on the floor with his clothes ablaze, while another man who was in the car was restrained. After airport staff extinguished his burning clothes the man got up and fought with the police shouting "Allah, Allah".

Stephen Clarkson, a bystander at the airport, helped police restrain the man who emerged from the vehicle with his clothes alight. "I managed to knock the guy to the ground. He was disorientated, otherwise I wouldn't have been able to do it because he was quite a big fellow," said Clarkson. "His clothes were practically burned from his body. He was just talking gibberish.

"There was one policeman on the scene more or less on impact. I think it was an airport official who put out the flames on the man. Immediately after that he got off the ground, still smouldering, and got to the boot of the Jeep and that's when the police approached him and tried to restrain him. He started fighting with the police."

"The second man walked into the terminal and walked out shortly afterwards.The Jeep exploded not long after the police told everyone to move back."

The injured arrested man was taken to Royal Alexandra Hospital under guard, where he is said to be in a critical condition with severe burns. Last night, the hospital was surrounded by a huge police presence. The other man was taken to Govan police station where he was questioned.

Other eyewitnesses talked of a repeated deliberate and determined attempt by the driver of the Jeep to ram the vehicle into the terminal building.

Thomas Conroy, a maintenance worker at the airport, said colleagues had seen a car hit the building. "There was a huge bang and then the car went up and the terminal itself caught fire," said Conroy. "A big Cherokee was rammed right into the entry doors. A woman said he tried to rev the wheels then, and someone saw him pour bottles of petrol over himself."

Eyewitness James Edgar said: "The driver tried to get through the main door frame, but the bollards have stopped him from going through. If he'd got through, he'd have killed hundreds, obviously."

The incident happened on the first day of the Scottish school holidays and coincided with the state opening of the Scottish parliament in Edinburgh by the Queen. First Minister Alex Salmond sat in on the Cobra meeting with UK ministers via a video link at St Andrews House.

Glasgow Airport remained closed last night and travellers were told not to go to there until further notice, while car traffic was prevented from approaching Edinburgh airport last night and other British airports tightened security. The White House said it was increasing security at US airports.

Mohammad Sarwar, Labour MP for Glasgow Central, which is home to the largest Asian community in Scotland, warned against jumping to any conclusions.

"This is very serious concern for all of us in Scotland and it will be horrifying and shocking for the people at the airport," said Sarwar. "My advice is to remain calm and not jump to any conclusions or speculation before the police initiate an investigation."

Hundreds of passengers were left stranded in the rain outside the terminal building and others remained aboard aircraft on the apron. Late last night, aircraft passengers were expected to be transferred to Glasgow's SECC for interview by police.

Marion MacKinnon, a BBC editor en route to Stornoway, said that the evacuation from the terminal building had gone smoothly. "We were upstairs in departures when the fire alarm went off and we were told that that we had to leave the building. We heard a lot of screaming and shouting from down below. People were running out from downstairs but upstairs things were quite calm until we saw smoke."

Western Isles Council convener Alex MacDonald was also trapped at the airport. "I didn't hear an explosion or anything else but we saw smoke as we left the building. We were sent out to stand in the rain about 200 feet from where the fire engines were still sending foam and water into the building. We've been told that we wouldn't be leaving tonight."