Arson is being blamed for two small fires early Sunday morning at a hotel being built along Lake Street in Minneapolis.

Fire crews arrived at the future Marriott site in the 1100 block of W. Lake Street about 4:15 a.m., said Assistant Fire Chief Bryan Tyner.

“The cause of this fire has been ruled arson,” Tyner said. The Fire Department did not say what led to that conclusion.

No injuries were reported and no one has been arrested.

“There really wasn’t any real damage,” said Ben Graves, chief operating officer for Graves Hospitality, whose company is having the hotel built.

Graves said there were “two little bonfires.” Whoever did it used plastic piping, insulation and some tools.

“The Fire Department said it looked like amateur hour,” he said.

One or more people involved climbed the fence, Graves said, noting that the locks were intact. He said additional security for the site is being considered.

The plan calls for roughly 120 rooms in the six-story Marriott Moxy hotel. Graves said he expects the hotel to open in October as scheduled.

Fire officials initially placed the fire near the Stone Arch Bridge in Minneapolis’ Mill District. A few hours later, the department corrected that information.