PHOENIX (AP) — A freeway crash early Sunday left two adults dead and two children critically injured and authorities were trying to determine if car racing was involved.

Phoenix police said the crash occurred on Interstate 10 just after midnight.

When officers arrived on the scene, they reported finding four people inside the crashed vehicle.

The names, ages and genders of the two adults who died haven’t been released yet.

Authorities said a 2-year-old boy and 4-year-old girl were rushed to a hospital in critical condition.

Arizona Department of Public Safety officials said investigators believe the vehicle was racing another car just before the crash occurred but driver impairment also has not been ruled out.