The U.S. Border Patrol's account of a fatal shooting in south San Diego, California, has been called into question by witnesses.

Authorities said a plainclothes agent shot 32-year-old Valeria Alvarado after she rammed him with her car Friday while he was serving a warrant.

"The suspect was armed with a vehicle, and literally ran our agent down," Border Patrol Deputy Chief Rodney Scott told KNSD-TV. "He was carried several hundred yards before he discharged his weapon through the windshield of the vehicle."

Alvarado, a mother of five, died at the scene. Scott said the unidentified agent was taken to a local hospital for treatment, but did not say whether the subject of the warrant was connected to Alvarado.

But witnesses' accounts Saturday portray the woman as driving away from the agent.

"He was walking towards the car and the car was moving back slowly," a nearby resident, Ayanna Evans told XETV-TV. "He pulled his arm up and I heard it, 'pop pop pop.'"

Another witness, Ashley Guilbeau, told KMFB-TV (Warning: graphic link) she saw the agent walking toward the front of the car shooting "about 12 times" without identifying himself as being part of the Border Patrol.

"Without her even able to say a word -- I didn't hear anything -- [he] just came across and just shot at the windshield many times," Gullbeau said.

A representative of an immigration-related advocacy group, the Southern Border Communities Coalition, told KNSD it will work with Alvarado's family to make sure the Border Patrol's investigation of the incident is transparent. On Saturday, her husband, Gilbert Alvarado, issued an angry call for justice.

"Whoever shot my wife, that guy whoever that is, that guy needs to get shot," he told ABC News.

KNSD's report, aired Saturday, can be seen below.