Police are hunting for two robbers who escaped with thousands of pounds from a Glasgow bank, after an initial suspect arrested during an armed siege was released without charge.

The drama began yesterday morning when two masked men walked into a bank in Glasgow's west end brandishing what appeared to be a gun. The robbers escaped from the Clydesdale Bank, in Byres Road, with a four-figure sum and fled down a lane behind the premises.

Police launched a massive search operation, climaxing in an armed siege around a guest house near Glasgow University. During the siege, which lasted almost an hour, three police marksmen aimed their guns towards a first-floor window of the Chez Nous guest house, on Hillhead Street.

As a crowd of students looked on, a man eventually emerged from the hostel with his hands up. A spokesman for Clydesdale Bank said the raid happened at about 9.40am, soon after the branch opened.

One customer was believed to be in the bank at the time but no-one was injured during the raid.

Margaret Gilmour, 51, who works in the Cancer Research UK shop, said: "There were just a few of us in the shop and we looked out to see a man running away from the bank and up the hill.

"He ran close to a lane and police were quickly on his tail. It all happened in a split second and I didn't get a very good look at him."

Beauty salon workers Gillian McLean, 30, and Elaine Ferris, 27, first realised there was something happening when they heard sirens in the street.

Ms McLean, who works for Revival Retreat, said: "We heard sirens and there must have been three or four police cars which came screeching to a halt outside the bank."

About six police vehicles were sent to the scene and officers, some of them armed, began searching the area surrounding Burgh Lane, down which the men are believed to have fled.

A police helicopter joined the operation and officers then cordoned off an area of Hillhead Street and Gibson Street.

Video footage shot by a resident shows a man emerging from the Chez Nous guest house at about 11.25am with his hands above his head.

With police marksmen aiming weapons at him, he walks slowly across the street and lies spreadeagled on the ground before being handcuffed and led away.

Student Andrew Faulkner, 19, who watched the siege unfold from his bedroom window, said: "I was woken by a helicopter outside and looked out to see armed police. An officer shouted for someone to come outside and make himself known. He came out and lay on the ground before being taken away."

A few hours later, Strathclyde Police issued a statement confirming that the man had been released without charge.

It read: "Around 9.30am this morning, two men with their faces covered, entered the bank, threatened staff with what appeared to be a firearm and demanded money. The men then fled the bank with a four-figure sum of cash and it was reported that they had run into a guest house in nearby Hillhead Street.

"An armed containment was placed around the guest house and a couple of hours later a man was detained by police in connection with the incident. This man has since been released without charge."

Police issued a description of the robbers. Both were white and in their 30s. One was wearing light blue jeans, a blue fleece and beige coloured baseball cap, the other a dark coloured woolly hat."

Anyone who has any information which could assist the inquiry is asked to contact Partick CID on 0141 532 3500 or Crimestoppers on 0800 555 111 where anonymity can be retained.