State investigators are on the trail of a string of fires that blazed through Massachusetts during the past month. At least 16 fires in the southeastern part of the state are thought to be the work of a serial arsonist or arsonists, prompting the Professional Fire Fighters of Massachusetts to offer a $5,000 award yesterday for information leading to the arrest of those involved.

Suspicious fires were reported in Quincy, Weymouth and other areas during the past month, and a four-alarm blaze in Fairhaven on Wednesday tore through a 19th century barn and a building of a landscaping company.

The spokeswoman for State Fire Marshal Stephen D. Coan, Jennifer Mieth, said that the state is relying heavily on the “public to be [its] eyes and ears” and that December has been a historically bad month for firefighters. Last December, two firefighters were killed, and in 1999, an act of arson in Worcester killed six.

Mieth said that fire officials have received numerous leads but won’t reveal why they think the fires are linked, according to the Boston Globe.

No injuries were reported, and most of the fires occurred in unoccupied buildings.

MAP: Towns Affected by Recent Spate of Arsons

View Suspected Arson Incidents in SE Mass. in a larger map