A grand piano inside a multiracial church in north Minneapolis was set ablaze in the first of a string of rapid-fire arsons that struck a section of the North Side late Thursday, and police were trying to determine whether racist graffiti found soon after on church property is connected to the arsons.

No arrests had been made by Friday night.

The racist scrawls were found on a church garage, but it's not known when that graffiti was written, a police spokesman said Friday night.

The fire inside the sanctuary of Community Covenant Church at 901 Humboldt Av. N. sent heavy smoke billowing from the building shortly after 11:40 p.m. Thursday. Firefighters contained the blaze to the piano, according to Assistant Fire Chief Cherie Penn.

Eight other fires were set between 12:27 and 12:57 a.m. Friday and charred a vehicle, trash cans, branches and a fence, Penn added. No injuries were reported.

"The piano is in ashes, much of the sanctuary is covered in soot" and walls throughout the church have been damaged by smoke, the Rev. Luke Swanson said, adding that he doesn't expect the building to be usable for several weeks.

Swanson said the church garage was tagged with the racist graffiti, which included the N-word and other "very hateful and racially motivated" messages aimed at blacks.

Sgt. Bill Palmer, a police spokesman, said the detective on the case reported that the racist graffiti was not noticed on Thursday. It was noticed before dawn Friday, not long after the fire was set.

"It's on a separate building. It's on a detached garage, and [the investigator on the case] does not know for sure whether they're related or not," Palmer said. No racist graffiti was found at the other arsons, which targeted a vehicle, a fence, trash bins and branches.

The blazes at Community Covenant and other locations were set within an area bound by Humboldt Avenue on the east, Thomas Avenue on the west, 2nd Avenue on the south and 10th Avenue on the north.

Palmer said they are believed to be connected due to the timing and proximity.

The area has been blanketed with fliers announcing a reward of up to $2,500 for information leading to the perpetrators. Anyone with information is urged to call authorities at 612-673-3070, 612-673-3389 or 1-800-723-2020.

jpowell@startribune.com • 612-673-7750 pwalsh@startribune.com • 612-673-4482