The policy sets Texas apart from other states, where firing at vehicles is rarely allowed, or forbidden. The Arizona Department of Public Safety does not allow its officers to shoot from moving vehicles or from helicopters. The California Highway Patrol permits firing on vehicles, but only to stop a threat and not to disable a car, and it forbids officers to fire from a helicopter in flight. The Nevada Highway Patrol, which does not use helicopters, does not permit shooting at vehicles during pursuits. Federal border patrol agents are not allowed to fire solely to disable a vehicle.

Two members of the State House committee that oversees the Texas police agency, Representatives Lon Burnam and Armando Walle, have asked for a hearing on the policy. René Guerra, the Hidalgo County district attorney, said he wanted the agency to end the practice of shooting at vehicles from helicopters.

“They need to look at their policy,” Mr. Guerra said. “There’s several ways to disable vehicles. I think D.P.S. will be put through very close scrutiny as to whether this was the best available means.”

The episode began about 3 p.m. on Oct. 25, when two state game wardens on patrol in rural Hidalgo County tried to pull over a suspicious red pickup on an unpaved road, the authorities said. The driver refused to stop and sped away, and the game wardens radioed for assistance.

The helicopter reached the truck after game wardens pursued it for nearly seven miles. Department of Public Safety officials said in a statement that the vehicle had appeared to have a covered drug load and was going dangerously fast. Because it was heading toward two elementary schools and a middle school, the truck posed “an immediate threat to the schoolchildren and motoring public,” officials said. The tactical flight officer who opened fire, Miguel Avila, shot the truck multiple times, but officials declined to say precisely how many rounds he had fired.

The Texas Rangers, a division of the Department of Public Safety, and the agency that oversees game wardens, the Parks and Wildlife Department, are investigating. In addition, state police officials requested that the Federal Bureau of Investigation and the civil rights division of the Department of Justice conduct an independent investigation. Officer Avila has been reassigned to administrative duties pending the outcome of the investigation.

Col. Steve McCraw, the director of the Department of Public Safety, said in the statement that the agency was reviewing all related policies, but he cautioned against rushing to judgment. “Although it is very tragic that two lives were lost, had the vehicle continued recklessly speeding through the school zone, any number of innocent bystanders or young lives could have been lost or suffered serious bodily injury,” he said.