UPDATE 2-At least 10 killed by Riyadh building explosion

(Recasts with deaths, injuries, description of scene)

RIYADH, Nov 1 (Reuters) - At least 10 people were killed when a fuel truck crashed into a flyover in the Saudi capital Riyadh on Thursday, triggering an explosion that caused the collapse of an industrial building, witness and television reports said.

Al Arabiya and Al Jazeera television stations reported at least a further 50 people were injured. They said 10 were dead and a witness at the scene told Reuters he had seen that many bodies.

The building, several storeys high, was almost levelled by the blast, with only one corner left standing. Several adjacent buildings were damaged and nearby vehicles, including a minibus on the flyover, were set on fire, witnesses said.

Television footage of the disaster and pictures posted on social media showed a body lying by burnt-out vehicles, and at least two charred bodies seated in a car.

A civil defence official at the scene, who spoke on condition of anonymity, said a petrol tanker had crashed into a concrete flyover. He and other officials were unable to give further details of the incident.

``I was inside the building when the blast came. Then boom, the building collapsed. Furniture, chairs and cabinets blasted into the room I was in,'' said survivor Kushnoo Akhtara, a 55-year-old Pakistani worker, who was covered in dirt and bleeding from multiple cuts over his body.

``My brother is still inside under the rubble. There are lots of people in there.''

Over a hundred emergency personnel were combing the wreckage on the flyover and searching for victims in the rubble of the building, which housed operations of Zahid Tractor, a distributor of heavy machinery.

(Reporting by Angus McDowall; Editing by Andrew Torchia and Patrick Graham)