A police watchdog is investigating after four people were killed when a car, police believe was stolen, turned into a fireball after crashing into a fish and chip shop in Bradford early today.

All four occupants of the Subaru died at the scene after it ploughed into the building in Killinghall Road, Laisterdyke, at 4.35am. Witnesses described the car burst into flames after a large explosion.

At a press conference today, Chief Superintendent Alison Rose, divisional commander of Bradford South Police, said: "At about 4:35am a serious road traffic collision took place on Killinghall Road, Laisterdyke, Bradford.

"A Subaru car – which is believed to have been stolen last night in the Daisy Hill area of Bradford – was in collision with a commercial premise.

"An officer at the scene pulled one person from the burning car but they died at the scene. A further three people from the car also died at the scene."

Chief Supt Rose added: "Obviously this was a terrible incident and the officers who went to the scene have understandably been affected by what they saw and are being supported by colleagues.

"Inquiries are ongoing and, because police were in the area at the time of the collision, the matter has been referred to the Independent Police Complaints Commission which is continuing to assess the situation.

The collision caused extensive damage to the premises of Killinghall Fisheries, part of which collapsed.

The crash scene has been cordoned off and road closures and diversions were expected to remain in place for most of the day.

Zac Hussein, who lives nearby, said he witnessed the crash. "My friend and I were sat in the car and we saw police cars moving up the street in a rolling road block," he said.

"They were moving slowly up the road at least two or three abreast. Then they moved past where we were parked and no more than eight seconds later we heard a crash and then almost instantly there was this huge fireball."

Mr Hussein said within seconds of the accident there were at least eight police cars on the scene, including one unmarked silver car containing what he believed to be a detective.

"One of the policemen called for me to get a fire extinguisher but obviously I didn't have one with me," he said.

"I came down to a phone box and called the fire brigade."

Mohammed Shaban, 32, the owner of Killinghall Fisheries, said he believed the car had crashed into the corner of the building where the gas mains supply was situated.

"There were four people in the car and I think they lost control and hit the side of the building," he said. "Because of where they hit the building, there was a gas explosion and I heard they all died at the scene.

"It's very sad. It's bad for me because it affects my business, but it's extremely sad that lives have been lost."

A fire crew from Bradford remained at the scene at 9am, along with the Cleckheaton Urban Search and Rescue Unit (USAR).

A West Yorkshire Fire Service spokesman said the USAR team was trying to shore up the building and had asked for structural engineers.

Police have urged all witnesses to the incident to contact Bradford South Roads Traffic Team on 0845 60 60 606."