The St. Paul Fire Department is investigating a series of fires that it believes were set intentionally Memorial Day weekend, from late Sunday night through early Monday morning.

The department posted on Twitter that it is asking the public for any information about 12 fires set during a roughly five-hour period.

The fires were concentrated in several neighborhoods in the west part of the city, namely Midway, Merriam Park and Macalester-Groveland, the department said.

Department photos show at least one fire in a garbage dumpster in a parking lot, another in an outdoor shed and several in alleys behind homes and businesses. Photos also showed several charred wooden structures.

“Fortunately nobody was injured and there were no fatalities,” Deputy Chief Roy Mokosso told KSTP-TV.

It takes longer for fires to be reported overnight, he said, adding to the threat for residents.

“Every minute a fire doubles in size, so it can quickly extend from a garbage can to a garage to a structure where people are living in and sleeping in at that time,” Mokosso told the station.

The department is asking people in those neighborhoods to check their security cameras for suspicious activity from about 11 p.m. Sunday to 5 a.m. Monday.

Anyone with information related to the fires should contact the St. Paul Arson Hotline at 1-800-723-2020.