LEWISTON (AP) — Authorities in Maine’s second-largest city say four overnight fires, including one that gutted adjacent apartment buildings and displaced about 25 people, were intentionally set.

Lewiston firefighters spent the pre-dawn hours battling the fires. No one was hurt.

The first fires were reported on Oxford and Nichols streets. Hours later, residents reported an explosion and fire on Howe Street, where neighboring, three-story apartment units were heavily damaged. Later, there was a another fire on Howe street.

Lewiston Police Chief Michael Bussiere said all four fires were set. He declined to discuss commonalities between the fires and said they could have been set by one person or a group.

The Howe Street apartments will be demolished, as will an abandoned single-family home on Nichols Street, Bussiere said. The other buildings were apartments, he said.

A fifth structure, an apartment building on River Street, was the subject of an attempted arson, Bussiere said. The building was not damaged, he said.

“Our job is to find out who did this, to keep the community safe,” Bussiere said.

The Red Cross is on the scene to assist displaced residents and a shelter has been set up.

Police declined to speculate during a news conference whether the fires were related to an arson spree in the area last spring.