ALTA, IA (AP) -

Two young sisters injured when a train hit the car they were in at a crossing in the northwest Iowa city of Alta have died of their injuries.

The Sioux City Journal reports that 4-year-old Chloe Binder and 2-year-old Camille Binder, of Alta, died Friday at a Sioux Falls, S.D., hospital, where they had been flown by helicopter after the crash Thursday. The children's mother, 37-year-old Heather Binder, of Alta, also was injured in the crash and is in fair condition at the hospital.

Heather Binder's 15-year-old son, Nathaniel Harmes, of Storm Lake, was driving. He's expected to be OK.

Authorities say Harmes didn't see the train when he drove the car across the tracks. Officials say the crossing has visual and audible warning signals, but no crossing arms.