A Saturday morning fire at a duplex in Windsor has caused an estimated $500,000 in damage and displaced two residents.

Fire crews responded to the property at the intersection of Irvine Avenue and Lillian Avenue at about 5:30 a.m. During efforts to control the blaze, one firefighter sustained a non-life-threatening injury.

Investigators determined the fire started on the main floor of the lower unit before spreading to the upper level. No occupants were inside either unit when the fire broke out.

According to Windsor Fire and Rescue Services, the blaze is believed to be accidental, though officials say an electrical cause has not been ruled out.