Authorities say arson is the cause of a fire that displaced several residents of a New Hope apartment building late Tuesday.

The West Metro Fire-Rescue was called to the Tradewinds Apartments on the 8100 block of 45th Avenue N. around 11 p.m. after a fire broke out in a stairwell, said Captain Scott Slawson.

As many as 50 people were forced out of their units. One resident, Lisa Palm, told KSTP-TV that she “could barely see” through the thick smoke as she ran down the hallway knocking on doors to make sure everybody go out.

Alarms in the three-story building did sound. No one was injured, the fire department said.

Crews from neighboring Plymouth and Golden Valley also responded.

Red Cross American volunteers were on the scene Wednesday morning helping 15 adults and four children, said spokeswoman Carrie Carlson-Guest.

The New Hope Police Department, West Metro Fire-Rescue, and the State Fire Marshal are investigating.

A reward of up to $2,500 is offered for information about the crime, Slawson said.