SURREY -- The RCMP is investigating the cause of an early-morning fire at a housing co-op to determine whether it was deliberately set.

The blaze at Hunter Hill Housing Co-op on 122nd Street near 70A Avenue began shortly before 3:30 a.m. on Monday. It started in a vacant unit in the building and spread to another, but was extinguished before anyone was hurt.

Surrey RCMP Cpl.Bert Paquet said the cause of the fire is unknown, but suspicious.

“There’s just some elements right from the offset,” he said. “Vacant townhouse, some people seen in the area shortly before the fire that we're looking into.”

Neighbours awoke to the roar of the flames, which were shooting through the roof and spreading next door.

“I heard the crackling, thought it was the trees at the dock falling so I came downstairs and looked out and it was engulfed in flames,” said neighbour Lisa Gordon.

"I was in the house and my brother was running downstairs saying there was a fire or something,” said Farah Elsaka, who lives across the street from the complex. “I went outside and it was just really bright and stuff. It was hot."

Damage to the vacant unit is severe, and smoke and water damage has forced the three people living next door seek temporary accommodation.

Police have closed off a large area surrounding complex as they look for evidence of arson. Neighbors told CTV News there was a stack of mattresses behind the house would've been an easy target for a would-be arsonist.