PORTSMOUTH TWP, MI -- Police are still looking for a serial arsonist who has been targeting parked vehicles -- and whose crimes have been intensifying -- in two Bay County townships.

Between April 7 and June 22, eight vehicles have been set on fire. Five of the incidents occurred in Portsmouth Township and three in Hampton Township.

"They're progressing," said Bay County Sheriff Fire Investigator Jeff Wolpert. "They started with some minor damages on vehicles around the fuel tank area. The last four fires had quite extensive damage to the vehicles."

One burned car was discovered Monday, June 18, on Trumbull Road.

Two more were discovered Friday, June 22, on Burns Road and on Cass Avenue, Wolpert said. They were reported about 40 minutes apart, he added.

Each vehicle had been parked in front of a residence. The damage transpired overnight with residents not observing the vandalism taking place, Wolpert said.

And the crimes appear random.

"There's no rhyme or reason they're being targeted," Wolpert said, adding police don't have any leads on a suspect.

The sheriff's office is encouraging citizens to be aware of their surroundings if they're out at night and to be on the lookout for anything odd. Any suspicious activity should be reported to 911, and those who may have information as to the firebug's identity is urged to call the sheriff's office at 989-895-4050 or CrimeStoppers at 1-800-422-5245.