Arson investigators are looking into an extra-alarm fire in a Rogers Park apartment building that injured seven firefighters and displaced several families, according to Chicago police.



A statement from the Police Department said its arson unit is assisting in the investigation of the fire, which broke out around 6 a.m. Monday in the 1700 block of West Estes Avenue. The department said no determination has been made yet about the cause.



Ald. Joe Moore, 49th Ward, has told reporters he was informed by fire officials that a possible accelerant was found in a stairway.



At least seven firefighters were injured, many of them from slipping on ice while battling the blaze in subzero weather, fire officials said. Crews briefly lost track of a firefighter, and a battalion chief issued a mayday alert, officials said. The firefighter was located shortly afterward.



As many as 25 residents were left homeless, officials said.