Police are investigating a Stamford house fire as arson, and officers say they are questioning a man.

The fire broke out at a multifamily home at around 12:40 p.m. on Highland Road.

Police say one of the residents in the house called 911 after she smelled gas and heard an explosion. She then allegedly saw a man running from the house. Police say they detained the man down the street from the scene.

Firefighters say the fire started in the stairwell leading to the second-floor apartment. The stairwell itself was badly damaged, as was the first-floor apartment, where the woman who reported the fire lives. Investigators believe some type of liquid was used to start the fire, having noticed a pour pattern on the staircase.

No one was hurt in the fire. The Red Cross is now assisting the families who were displaced.