By Angus McDowall

RIYADH, Nov 1 (Reuters) - At least 22 people were killed when a fuel truck crashed into a flyover in the Saudi capital Riyadh on Thursday, triggering an explosion that brought down an industrial building and torched nearby vehicles, officials and state media said.

Health ministry spokesman Saad al-Qahtani said 135 people were injured in the disaster. He told state television they were mostly men and included some foreigners.

The civil defence department said a gas tanker had hit a bridge in eastern Riyadh, causing a gas leak and an explosion in a nearby heavy machinery and vehicles warehouse, according to the state news agency SPA.

"The truck driver was surprised by a road accident on its route, causing it to crash into one of the pillars of the bridge," spokesman Captain Mohamed Hubail Hammadi said.

Although the incident took place near the headquarters of the Saudi Arabian National Guard and the Prince Nayef Arab College for Security Sciences, officials speaking on state television said it was an accident.


DRIVER BLAMED

The civil defence chief, Saed al-Tweijri, said the fire had been brought under control. He blamed the tanker driver for the accident.

The warehouse, several storeys high, was levelled by the blast, which also caused severe damage to other neighbouring buildings. Rubble, twisted metal and shattered glass littered a wide stretch of the surrounding area.

"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 Akhtar, a 55-year-old Pakistani worker, who was covered in dirt and bleeding from multiple cuts on his face and hands. "My brother is still inside under the rubble. There are lots of people in there."

The blast, which struck at around 7.20 a.m. local time, was on one of the capital's busiest roads but because Saudi Arabia is still observing the Eid al-Adha holiday, traffic was lighter than normal.

An hour after the explosion, fires still raged in cars and trucks nearby and a column of black smoke billowed over the area.

Dozens of burnt-out vehicles surrounded the scene of the blast, including a small bus and other cars on top of the flyover, which was left buckling after the incident.

Television footage and pictures posted on social media showed a body lying by smoking vehicles and at least two charred bodies seated in a car. Another blackened corpse was visible in the remains of a truck.

More than 100 emergency personnel were combing the wreckage on the flyover and searching for victims in the rubble of the building, which housed the operations of Zahid Tractor, a distributor of heavy machinery.

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