Authorities say it appears that the fatal apartment fire in Mount Vernon Monday night was accidental.

The fire broke out around 5:30 p.m. in a 16-unit legal boarding house on South First Avenue.

When firefighters arrived, they say they found a man in his 60s, already deceased, in the apartment’s living room. A female victim was discovered in the kitchen, in cardiac arrest.

Crews were able to revive her, but she’s still in critical condition at Jacobi Medical Center.

Although the fire was contained to the one apartment, all the other tenants had to be evacuated. They waited hours to return home.

Fire officials are working to pinpoint what sparked the blaze.