SPRINGFIELD -- A string of set fires in the Bay neighborhood has prompted the Springfield Arson and Bomb Squad to look to the public for help.

City firefighters have responded to a half-dozen or more mostly-minor arson fires along Bay Street over the last year-and-a-half, Dennis Leger, aide to Commissioner Joseph Conant, said.

"We think we have a firebug over there," Leger said.

The most recent fire was reported at about 5:35 p.m. on Tuesday behind a vacant commercial building at 846 Bay St., Leger said.

"We had some trash and a mattress burning behind the building," he said, adding that the building did not catch on fire. The building was once home to Cohen Brothers Recycling, Leger said.

Leger said the most serious fire involved a tractor trailer that had tires inside.

Those with information are asked to call the arson squad at (413) 787-6370. Those who wish to remain anonymous can use the "Text-a-tip" program. Text "CRIMES" or "274637;" the body of the message should begin with the keyword "SOLVE," followed by the information to police.