Fire engulfs a structure during a wildfire in Escondido, Calif.

SAN DIEGO - A 57-year-old man has been charged with setting one of 10 wildfires that swept the San Diego region this week.

Alberto Serrato pleaded not guilty Friday to arson in connection with a 105-acre fire in suburban Oceanside - one of the smaller fires. The fire started Wednesday and is fully contained.

Tanya Sierra, a spokeswoman for the San Diego County district attorney's office, says witnesses saw Serrato adding brush to the flames near homes but he was not seen starting the fire. The spokeswoman says he has not been connected to any other fire.

The spokeswoman says Serrato was arrested Thursday in Oceanside and faces up to seven years in prison if convicted.