SAN ANTONIO – The incident happened around 11:40 p.m. Thursday in the 6900 block of San Pedro Avenue near Oblate Drive.
The man had been throwing rocks at cars as they were passing by.
One of the rocks struck a pickup truck, which then turned around and confronted the man, police said.
The driver, identified as a 38-year-old man, told police he hit the man with his truck after he believed he saw the man was armed, according to a preliminary report from SAPD.
Police detained the driver and the passengers at the scene. The driver could possibly face a charge of aggravated assault, police said in the report.
Police said the 18-year-old man was taken to the hospital with life-threatening injuries.