The number of fires believed to be linked to an arson spree has risen to 39 across the Los Angeles area, fire officials said Sunday.

A total of 32 fires have been set in Los Angeles and seven others in neighboring West Hollywood since the suspected spree began Friday, Assistant Chief Patrick Butler of the Los Angeles Fire Department said. Seven of those fires occurred Saturday night, with one described as "significant," though only cars were damaged, fire officials said.

A joint task force comprised of city and county fire officials and police departments is investigating the string of fires.

Despite a $60,000 reward, authorities had not made an arrest by Sunday. Police are asking residents in the area to bring forward any surveillance video from their properties that might show suspicious activity. Residents are also being encouraged to follow the "see something, say something" motto and report suspicious behavior to authorities.

Officials sought Sunday to show their commitment to finding the person or people behind the fires.

"We're not going to rest and we're going to put all the resources out there," Butler said.

They also asked residents to help deter the perpetrator by leaving porch lights on and locking their vehicles, as many of the fires were set using a car as the incendiary device.

"Auto fires, as soon as they get going, they get really hot, really fast," Butler said. "They essentially give off their own combustibles."

Some of the fires spread to nearby buildings, though no injuries have been reported. Among the homes damaged was one that was once occupied by The Doors frontman Jim Morrison.

"When you have millions of people living with millions of cars in these very dense neighborhoods, this is becoming a new form of domestic terrorism that really has got our community in a very bad spot," West Hollywood Mayor John J. Duran told CNN Saturday.