The Santa Rosa Fire Department is investigating several suspicious brush fires.
Over the weekend, firefighters went to the area of Hearn Avenue and the railroad tracks for a number of calls for brush fires.
Crews found three fires, and a short time later, more calls about fires breaking out in another location.
"This is where one of the fires occurred right off of the road along and second one just down 50 yards on the trail. We had a total of 13 fires and now looking for the public's help," said Sgt. Marcus Sprague with the Santa Rosa Police Department.
Sgt. Sprague says the biggest concern is that it's getting drier out.
"We live here, we don't want another big fire storm. We are just starting to rebuild."
Authorities say so far, their evidence points to someone or several people on bicycles.
"No indication of tools, but probably someone on a bike," he said. "Please call if you were out Saturday night around midnight."