The Harris County Precinct 5 Constables said a Cadillac was pulled over on side of the Beltway near Bellaire around 1:30 a.m.
Investigators say a Nissan crashed into the Cadillac, ejecting a woman out of the vehicle.
The man who was in the vehicle with the woman tried to give her CPR when he was struck by an oncoming truck. The woman he was assisting was also hit and killed.
The man was transported to the hospital in critical condition.
Both drivers of the Nissan and truck are being tested for possible DWI.
The woman has not been identified.