An unoccupied house in Merrick was badly damaged in a fire Monday.

Authorities say it happened on Lindgren Street around 10:15 p.m.

Merrick, Freeport and Bellmore fire departments worked together to put the fire out.

A firefighter from the Merrick Fire Department suffered heat exhaustion but was treated at the scene and is expected to be OK.

The cause of the fire is under investigation.