The three suspects, one white and two black, were led from the bus and searched by the side of the road.

All three were handcuffed and then put into cars while officers searched the bus.

Plain clothes officers, a dog unit and forensic teams were all present and witnesses saw a weapon being recovered from the bus.

An eyewitness at the Ifield roundabout said: "I saw the helicopter above and then saw the police cars screeching along the road. You could smell the burning rubber.

"The police jumped out of the cars and had guns and there were just people on the floor all around the bus.

"We saw the three blokes being patted down and handcuffed. I have never seen so many police in one place in my life. I knew that it had to be something big."

Another witness said: "I saw the police come off the bus with three blokes and a gun in a plastic bag.

"There were about six pensioners on the bus who were taken off and transferred onto another one. They were really lucky that no-one had been hurt as it's mostly pensioners that use that bus."

The Police closed Ifield Avenue going towards the Ifield Roundabout while the bus was searched.

Duty Manager of Southdown PSV, James Scanlon, said: "The bus was delayed for a few minutes while the police descended on it.

"I went out to the scene to assist the driver who was fine and has carried on with his shift today. I took the rest of the passengers to their destination in my car.

"The suspects were on the grass and in handcuffs. There were four people of pensioner age on the bus and a teenage girl and all the passengers were unharmed by the incident and remained at the scene to give statements to the police.

"We replaced the bus with another one while the police carried out their search."

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