An Arizona Department of Public Safety spokesman says a car slowed on Interstate 10 Saturday afternoon to look at a minor collision and cut off a minivan, which braked to avoid a crash.
A small sedan then hit the minivan, and a gas tanker hit the two vehicles and overturned on its side.
A 13-month-old girl, a 2-month-old boy, and a woman believed to be their mother were critically injured in the sedan and taken to hospitals; the babies died around 3:45. A woman in the minivan suffered nonfatal injuries, and the tanker driver was not hurt.
DPS is looking for the male driver of the white or gray Dodge Magnum that cut off the minivan.