A gun-toting teenager who caused armed police to be called to the City of Bristol College has been jailed for six months.

Samia Shakoor, 18, had a grudge after being expelled and pointed the BB gun at security guard Philip Amesbury, Bristol Crown Court was told yesterday.

Her actions prompted police with guns to swoop on the scene, ordering her to drop face down on the pavement and arresting her at gunpoint.

Shakoor, who had no previous convictions, collapsed in the dock as she was handed the sentence and had to be helped by her mother.

Shakoor, of Glenfrome Road, Eastville, pleaded guilty to possessing a firearm with intent to cause fear of violence in February.

Imposing sentence, Judge Michael Roach told her: "It may have been a prank, but this sort of offence is regarded very seriously by the courts. You may have known it was only a BB gun but to those who saw it, it would have been immensely frightening. You were in possession of that weapon, on a busy street, close to the city centre and pointed it at passing cars and people. This is not a minor offence."

James Tucker, prosecuting, said Shakoor was a student at the college described as having a "very nice manner". He told the court, though, that her attendance became poor and she developed unruly behaviour which included swearing at staff.

Having been expelled in July last year, she was re-admitted only to be permanently excluded the following month and had to be ejected from the college a number of times – including by security guard Mr Amesbury.

Mr Tucker said: "On February 3 this year a man in a woolly hat complained to Mr Amesbury he thought he had been hit in the head with a stone. Mr Amesbury saw the defendant in a black Nissan Micra and she was pointing a BB gun at him. He heard a pop, which he believed was the gun going off; he believed it was a BB or airgun."

The court heard a lecturer standing at a window observed Shakoor holding the gun out of the vehicle, and two students saw a man hand her the weapon before she pointed it.

Mr Tucker said: "The defendant fired it at a passing vehicle and, as a result, the police were contacted.

"Because of the nature of what was reported a tactical firearms team was activated by a codeword and an unmarked car pulled up and they drew live weapons."

Virginia Cornwall, defending, said: "It was an immature act. It was more of a prank than anything else."

Miss Cornwall said her client had given very little thought to the consequences as her friends had used the gun to shoot at each other.

The court heard Shakoor had suffered emotional difficulties in the past but was from a law-abiding, respectable family and was believed to have promise for a better future.