A bus driver has been suspended after a rogue vehicle ploughed through the city centre when he ‘stopped to buy a drink’.

Horrified onlookers watched as a First bus careered down Renfield Street yesterday, around 3.45pm.

The driver stopped at a bus stop near West Regent Street and is understood to have gone to a bakery and then a newsagent before reportedly realising his handbrake was off. The bus then rolled 300ft downhill.

Two people were taken to the Royal Infirmary following the incident, but are not thought to be in a serious condition.

Read more: Video: Runaway bus causes chaos In Glasgow after careering down busy city centre street

Bystanders told the Evening Times they saw the Easterhouse-bound number 60 bus rolling down the street “with the driver chasing after it”, before it smashed into a blue Renault Twingo car and three other buses.

Ali Hafiz, who was manning the till in RF News on Renfield Street, said the bus driver came into his shop to buy a drink - only to turn round and see his vehicle rolling away without him.

First bosses have said it is “too early to speculate” on the cause of the incident and have now launched a probe.

A First Glasgow spokesman said: “We can confirm that a First Glasgow vehicle was involved in an incident on Renfield Street this afternoon.

“Its too early to speculate on the cause of the incident. However, we’ve launched an immediate investigation and will work closely with the emergency authorities to determine exactly what happened.

Read more: Video: Runaway bus causes chaos In Glasgow after careering down busy city centre street

“Our thoughts at this time are with the two men who were injured as a result of the incident.

"As per our procedures the driver concerned has has been relieved of his duties while we undertake a detailed investigation."

Shop worker Ali said: “The driver was in my shop for a good two minutes before he realised he’d left the handbrake off.

“He had already been in Greggs, like a lot of bus drivers do when they stop here.

“He rushed out as soon as he realised his bus was moving slowly down the hill, but it still crashed into the Stagecoach bus.”

Manager of Indian restaurant Charcoals watched the incident unfold while serving a customer.

Muhammad Sultan, 36, said: “I was just chatting to a regular customer sitting over here by the window.

“I heard a ‘boom’, like a blast, and suddenly I looked outside and saw this bus coming down.

“The Stagecoach bus was pulling out, and the First bus just hit into it. It was out of control, it was packed out.

“The passengers were really in shock. They weren’t hurt, I don’t think, except the driver.”

Read more: Glasgow runaway bus crashes after driver goes to buy a drink

Muhammad and his team said he helped the male driver of the single decker Stagecoach, which took the brunt of the rogue vehicle’s force.

An emergency exit door on the side of the Stagecoach bus had been pushed open, allowing passengers to escape as the main door was blocked.

Muhammad said: “The driver felt shocked, he had a sore neck and then he had a pain in his wrists.

“I gave him some water to drink and asked him if he was okay.

“I’ve never seen this before.

“It was the first ever time I’ve seen that, it was such a shock for me, four buses. It was really scary.”

Another by passer who witnessed the terrifying scene said: “I saw the bus going down the street with the driver chasing after it.

“God knows why he wasn’t in the bus - the whole thing was empty.

“The bang was unbelievable.

Read more: Glasgow runaway bus crashes after driver goes to buy a drink

“It hit a car and the driver was lying on the ground for about half an hour.

“It hit three other buses and stopped.”

The man, who did not want to be named, said the out of control bus was stationary at a stop on Renfield Street, just before the junction with West Regent Street.

He said: “The bus was sitting up beside the bookies and the driver got out before the bus went right down the street.

“I don’t know what he was doing out of it, only he knows that.

“The fellow from the blue car was lying on the road for about half an hour.”

Hundreds of people were in the city centre yesterday enjoying Fair Monday in the warm weather.

A number of city centre streets were already closed due to filming for Trainspotting 2, leading to heavy congestion in the area prior to the incident.

Dozens of people stood watching as police and emergency services helped those involved, and directed traffic away from the scene.

At least 15 police officers were on site, with many interviewing witnesses and taking statements.

A police spokeswoman said officers are reviewing CCTV and have appealed for information about the incident.

She said: “Around 3.45pm police received a report of a bus apparently travelling south on Renfield Street having collided with a stationary car at traffic lights at West George Street.

Read more: Glasgow runaway bus crashes after driver goes to buy a drink

“The car moved forward and struck a pedestrian on Renfield Street.

“The bus continued to travel on Renfield Street before it collided with a stationary bus near to St Vincent Street, which then nudged into another stationary bus on Renfield Street.

“Two men have been taken to the Glasgow Royal Infirmary for treatment to injuries.

“Enquiries are ongoing to establish the exact circumstances of the incident, including reviewing CCTV footage, and anyone with information is asked to contact Police Scotland on 101.”