Dallas ? A man squeezed through the sunroof of a Jaguar early Tuesday and opened fire with an assault rifle on another moving vehicle, killing three men and critically wounding a fourth, police said.

Authorities were searching for the gunman and two others who may have been riding in the light-colored Jaguar with fancy wheels, police said.

University Park Police Capt. Robert Brown said the shooting may have stemmed from a scuffle at a bar earlier in the evening. He said the shooter apparently waited for the other party to leave the bar, and then followed in the Jaguar. The shooting occurred around 2 a.m. on a highway frontage road near the Southern Methodist University campus, police said.

“Apparently, there was a dispute on the dance floor in which somebody got hit or punched,” said Mike Turiace, who was tending bar at Jack’s Pub & Volley Ball club Monday night. “The guy just got angry and decided to pursue it.”

A police officer waiting at a traffic light at the intersection witnessed the shootings and stopped to help when the gunned-down car crashed, Dallas Police Sgt. Gil Cerda said. Police policy prohibited the officer from pursuing the fleeing Jaguar because he already had a prisoner from an unrelated case in his back seat.

Turiace and others said Jack’s Pub is normally a safe, friendly place that hosts festivals and volleyball matches and attracts a college crowd from SMU.

But the clientele shifts a bit on Monday nights, when the bar advertises $2 drinks and a packed dance floor thumping with two DJs.

Tonya Hernandez, center left, and friend Marcela Castillo, 17, console each other at the site of a multiple homicide early Tuesday near Dallas. A man in a Jaguar stood up through the sunroof and opened fire with an assault rifle on another moving vehicle early Tuesday, killing three men and critically wounding a fourth, police said.

“There’s arguments, there’s altercations, people that need to be escorted out, just like any other bar,” the bartender said.

Turiace said the fight didn’t cause a big stir in the crowded pub, but its policy is to escort instigators outside after a fight.

“It wasn’t anything out of the ordinary that would lead to this. I guess certain people have it in their minds that this is their type of proper justice,” Turiace said. “That really scares me.”