Police say arson is behind the explosion that rocked a Vancouver business area early Wednesday morning.

They now believe that a fire was set inside a restaurant with the use of an accelerant. That led to an explosion that ripped through the Taco Del Mar restaurant and its neighbouring Starbucks at about 2:30 a.m.

"The explosion was an air fuel explosion," Vancouver police Const. Tim Fanning told reporters gathered outside the scene on Wednesday afternoon.

An air fuel explosion occurs when an accelerant ignites in the air and blows up.

"I can't tell you what type of accelerant was used. Of course, there's a lot of forensic work that needs to be done."

No one was hurt by the explosion, which scattered crushed metal and broken glass across the street and sidewalk at 686 West Broadway.

Witnesses have said a man ran from the scene and threw away burning clothing. Police say they will examine video surveillance tapes from the area.

The explosion was so powerful that it shattered a window on the sixth floor of a Holiday Inn across the street. A resident inside was startled but physically unhurt.

David Goguen, the manager of the Broadway Holiday Inn, told CTV Newsnet that he arrived to a surreal scene shortly after the explosion.

"It was quite a strange situation because the whole front of the London Drugs looked like it had been bombed or collapsed," Goguen said.

"It was just one big mangled mess."

Goguen said the collateral damage to other businesses in the area can only be described as being caused by a "sonic blast."

Police and firefighters continued to sift through the damage on Wednesday afternoon after speaking to witnesses. Earlier in the day, one witness had told CTV they saw a person fleeing the scene on foot.

CTV British Columbia's Maria Weisgarber, reporting from the scene of the blast Wednesday morning, said, "There (was) debris all over the place and broken glass."

She added that "a coffee shop, a clothing store, and four or five business have suffered damages as the result of this explosion."

People in the area reported hearing a loud blast and feeling a tremor, Weisgarber said.

Anna Jekli told The Canadian Press she was woken from sleep in the early hours.

"It was just a big bang and then I was just waiting for the sirens," she said at the scene, adding that she was shocked at the damage.