An explosion at a building in Harrisonburg, Va., on Saturday morning left a structure engulfed in flames and five people injured, including three James Madison University students who had gathered for an event nearby.

Harrisonburg city spokesman Mike Parks said several people called 911 to report hearing an explosion around 8:30 a.m. Saturday at a strip mall on Miller Circle, just a few blocks west of the James Madison University campus.

In a tweet, Gov. Ralph Northam (D) said that the blast was a gas explosion and that his staff was monitoring the situation.

Firefighters arrived to find a three-alarm blaze. Two people were found injured at the scene and flown by helicopter to University of Virginia Medical Center, where they were in stable condition Saturday afternoon.

Three James Madison University students, who had assembled near the strip mall for an event, had minor injuries from being struck by debris, according to the university and Parks. One of the students was treated at a hospital; the other two were treated at the scene and released.

On Saturday afternoon, Parks said firefighters had conducted a preliminary search and had not found evidence that anyone else was in the building when it exploded.

Footage from the scene showed the charred remains of the building engulfed in smoke and flames. Two ladder trucks were battling back the flames nearly two hours after the explosion was reported. The blast was so forceful that it rattled the windows of nearby homes.