BERKELEY (CBS SF) — Two homes were damaged and five people displaced by a fire early Sunday morning Berkeley firefighters believe started in a recreation vehicle parked in a driveway.

Berkeley Fire Department Chief Dave Brannigan said firefighters responded to a call at about 4:35 a.m. in the 900 block of Delaware Street, about two blocks north of University Ave.

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A fire in the RV spread to the houses on either side of where it was parked, Brannigan said. The fire was under control about a half-hour after firefighters arrived.

No firefighters or occupants of the houses or RV were injured, but the houses were damaged to the extent that five people were displaced, from the RV and both houses. The cause of the fire remained under investigation Sunday night.

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Meanwhile, firefighters early Sunday morning were still battling a six-alarm fire at a multi-story apartment building under construction in the2000 block of University Avenue in downtown Berkeley. Nearly 100 firefighters, including many from other departments, were fighting that firewhen the Delaware Street fire was reported.

It demanded more mutual aid from outside departments be called, Brannigan said.

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“It’s unusual to get two large fires like that going at the same time,” he said.