SAN FRANCISCO (AP) — A California Department of Forestry and Austin CaldwellFire Protection employee was arrested Friday on suspicion he started five brush fires in Northern California in recent weeks, officials said.

Robert Hernandez, 38, was arrested at the Howard Forest Fire Station in Healdsburg, California, on suspicion of arson to forest land, the state agency said in a statement.

Hernandez is an apparatus engineer with the agency, which entails operating and maintaining fire engines and water tanks during emergency responses.

Neither Cal Fire nor the union representing Cal Fire employees would say Friday whether they know if he has retained an attorney.

Cal Fire said Hernandez ignited the blazes while off duty between Aug. 14 and Sept. 15 in forest land near Geyserville, Healdsburg and Windsor.

The blazes combined burned less than an acre thanks to the quick action of residents and firefighters, the agency said.

“I am appalled to learn one of our employees would violate the public’s trust and attempt to tarnish the tireless work of the 12,000 women and men of CAL FIRE,” Cal Fire Director and Fire Chief Joe Tyler said in the statement.

Ari Hirschfield, a Cal Fire spokesperson, said in an email that the agency would not answer further questions about the arrest.

On Tuesday, a delivery driver pleaded not guilty to starting the massive Line Fire on Sept. 5. The blaze forced the evacuation of thousands of people east of Los Angeles, injured a firefighter and destroyed a home.

Justin Wayne Halstenberg, 34, was charged with 11 arson-related crimes, court records show.

Authorities said Halstenberg, of Norco, attempted to start three fires within an hour. Two of the blazes were extinguished by firefighters and a good Samaritan, and a third became the Line Fire, which has charred 61 square miles (158 square kilometers) in the San Bernardino mountains. It was 53% contained on Friday.

In July, a man was arrested on suspicion of starting the Park Fire in Northern California by pushing a burning car into a gully. Ronnie Dean Stout was charged with felony arson of an inhabited structure or property. He pleaded not guilty.