A large explosion has blown the top off a shopping plaza in Waukegan, Illinois..

Waukegan - A large explosion has blown the top off a shopping plaza in Waukegan, Illinois.

Police say at least six people have been taken to a hospital after the explosion struck around lunchtime today.

It blew the windows out of storefronts and collapsed the ceilings above stores.

Witness Candi Rixie was taking orders at a sandwich shop a block away.

She says she felt a rumble, almost like somebody hit the building with a car.

It’s not immediately clear what caused the blast, but crews from the gas company are on the scene to investigate.

Fire crews from several towns have come to help in rescue efforts, and are searching to see if people are trapped inside.