PULLMAN — Residents in Pullman are on edge after authorities said an arsonist was responsible for three fires in a week at Washington State University.

The latest fire was reported just after midnight Tuesday in a veterinary school building on campus, said fire Capt. Eric Reiber. Someone apparently broke in through a window and set multiple fires in the building, Reiber said.

No one was in the building when the fire broke out. A fire Saturday also burned a two-story community building at the Chief Joseph apartment complex and an arson last week burned a community building at the Nez Perce apartment complex, Reiber said. Both are university housing.

No one has been injured in any of the fires. No motive or a suspect has been offered. Fire and police officials asked the public for help in finding the arsonist.

The latest fire was contained by sprinklers, and most of the loss appeared to be water damage. Firefighters and WSU police searched the building, and found a broken window, said Mayor Glenn Johnson, who is spokesman for the fire department.

“We found several points of ignition,” Johnson said.

Investigators are using a fire-tracking dog from Spokane police to find evidence, Johnson said. They are also studying images from surveillance cameras around campus, Johnson said.