Mount Vernon investigators are looking into the cause of a fire that has left eight people homeless.

It could be days before the origin of the fire at 214 Union Ave. can be determined, investigators say. The fire started at about 6:30 a.m. Tuesday and quickly spread to the house next door, displacing four families.

Tenants who lost their homes claim squatters frequently came in and out of 214 Union Ave., which was abandoned and undergoing renovations.