An altercation on Interstate 10 led to shots being fired and sent a man to the hospital.
San Antonio police said gunshots were reported around 10:30 p.m Thursday.
Investigators believe there was an argument on the highway between the victim and four men riding in gray Chrysler 300 when the victim and his passenger were fired upon by someone in the Chrysler.
A bullet grazed the victim's head, but he still managed to drive his SUV to a nearby gas station at I-10 and Hildebrand to call paramedics. He was transported to the hospital with critical injuries, police said.
The victim's passenger was reportedly not injured. The four men in the other vehicle had not been located by SAPD as of 6 a.m.