Authorities are investigating a fire that broke out in a GCU residence hall on Sunday

PHOENIX. Authorities are investigating the cause of a fire that broke out Sunday morning in a Grand Canyon University residence hall.

Around 9:30 a.m., the Phoenix Fire Department was called to GCU for a fire alarm on the third floor of a mid-rise building.

When firefighters arrived, they saw no smoke or fire. When they got to the third floor, they found smoke in the hallway, officials said.

Firefighters used hoses to extinguish the fire and search for everyone in the rooms. The fire was contained and extinguished in the common room.

Officials say a sprinkler system was activated, keeping the fire contained to one area until firefighters arrived to fully extinguish it.

There are no reports of casualties.

GCU officials say the fire contained mostly a piece of furniture in the living room, but water and smoke damaged the six units, which consist of four single bedrooms, two bathrooms and a shared living area and kitchen.

Twenty-four students who lived in these units were temporarily relocated to other rooms on campus.

GCU says the Phoenix Fire Department and Phoenix Police Department are working to determine the cause of the fire, including the possibility of arson.