An after-hours explosion in an Abbotsford, B.C., bar sent equipment flying into the street and put one man in hospital in serious condition Sunday night.

The explosion occurred at around 11:30 p.m. at the Rain Grill and Bar on South Fraser Way, sparking a fire that destroyed the building.

The bar had been closed for a few hours when the blast occurred, but one 39-year-old man who was either inside or near the building at the time was badly burned.

He remains in hospital in "serious and grave" condition, said Const. Ian MacDonald.

"The explosion caused windows in a neighbouring business to break, and some equipment and furnishings were blown outside," MacDonald said. "If you were in the middle of that vortex you would obviously suffer a great deal."

The victim's connection to the bar has not been established.

Police are treating the fire as suspicious, MacDonald said.

Two other fires, both considered suspicious by police, have been investigated at the establishment under its previous names LAX and Madison's.

Traffic is being diverted on South Fraser Way between McCallum Road and Bourquin Crescent as police gather evidence.

"We've established a pretty large perimeter because of the damage to neighbouring businesses," MacDonald said.

The road is expected to open up on Monday evening.