The police and fire departments in Los Angeles are on high alert as a spate of arsons enters a third day.
There were more than 30 fires from late on Friday to early Saturday in the Hollywood area. These included 13 vehicle fires.
According to the Los Angeles Times, there were 21 fires in Hollywood and West Hollywood the previous night.
In many cases, the fires appeared to have been set within minutes of each other.
The BBC reports it is one of the worst arson sprees in recent times.
The Federal Bureau of Alcohol, Tobacco, Firearms & Explosives is offering a reward of $US60,000 for information leading to the arrest of those responsible.