Investigation Underway After Explosion Injures 5 People In Evanston

EVANSTON, Ill. (CBS)-- A house fire left five people injured in Evanston Tuesday night.

The Evanston Fire Department responded to the house on Brown Avenue after a call came in for an explosion.

Police said based on an initial investigation, a person broke one of the first floor windows and threw an "unknown" explosive device inside the house.

"The device detonated causing significant damage to the house, including breaking some or all of the first floor windows," Police stated in a written statement.

The Evanston fire chief said based on the scene, it did not look like the fire started in a natural way.

Five people were rescued from the house and treated for injuries.

A witness said he initially thought he heard thunder, but went outside and heard a mother calling for help from the house. He said the mother was trying to escape out the window and handed him a child.

Officials are investigating.