CUMBERLAND, R.I. - An arsonist appears to be on the loose just over the North Attleboro border.

Police and firefighters continue to investigate four suspicious fires in the same area within a week.

Two blazes took place Tuesday night in an office park off Mendon Road.

A tractor-trailer was discovered engulfed in flames, and an office trailer was also found on fire a few hundred feet away but wasn't as badly damaged, fire officials said.

The previous Tuesday night, two fires broke out in two Mendon Road businesses, one that destroyed Roberta's Hair Salon and the other that damaged Everybody's Favorite Family Restaurant. Assistance from North

North Attleboro firefighters assisted with some of the fires.

The state fire marshal has determined the first set of fires appeared to have been set.

The fire marshal's office and Cumberland Crime Stoppers, a citizens group, are each offering $1,000 rewards for information.