iStock/Thinkstock(HOUSTON) — A 7-year-old girl was shot and killed in a Walmart parking lot in Houston early Sunday when a gunman opened fire on a vehicle she was traveling in with her mother and three other young girls, authorities said.The girl, who has not been identified, was leaving the Walmart at 15491 Wallisville at Beltway in the Wallisville section at about 7 a.m. when an unknown man shot into their car, according to the Harris County Sheriff’s Office. “Mother & daughter were in a car leaving a store when an unknown male began shooting into their car for an unknown reason,” Sheriff Ed Gonzalez tweeted.Jesse Razo, a major with the Sheriff’s Office, said a news briefing that the suspect was driving a red pickup truck with no plates.The suspect “pulled up next to the vehicle and began shooting into the vehicle,” Razo said. The girl’s mother was shot, too, Gonzalez said. She was wounded in the arm but is expected to survive, officials said.In addition to the girl and her mother, two teenagers and a younger girl were also in the car, Gonzalez said: the teen girls were not hurt, and the girl suffered “glass fragment injuries.”Razo said the girls were “shaken” and “devastated.” The suspect, who was wearing a red hoodie, fled in a red truck, Gonzalez said. He was described as being in his 40s and having a beard, Razo said.He was still at large as of Sunday morning.“He is considered armed and dangerous,” Razo said.The motive for the shooting was not immediately known. Homicide detectives were scouring the area and checking surveillance video for clues.“We’re going to use all resources available to bring this killer to justice,” Razo said.He urged the suspect to surrender.“Because we will be looking for you, we will locate you, we will find you,” Razo said.The Sheriff’s Office urged anyone with information to call 911, tweet at @CrimeStopHOU or call 713-222-TIPS.Copyright © 2018, ABC Radio. All rights reserved.