Alexia Cortes sat in her family’s minivan with her three younger siblings on a hot July afternoon in 2020. The vehicle was parked on Whittier Boulevard near Durfee Avenue, the engine running and the air conditioning blaring, while her parents shopped at La Mano Tortilleria in Pico Rivera.

Suddenly, a man they did not know jumped into the driver’s seat, looked at them and said “Vamonos,” or “Let’s go.” Cortes, who was 17 at the time, tried to hit the intruder; her siblings rushed to help. But the man did not say another word or look at them. When Cortes opened the unlocked sliding door to escape, the man put the car in reverse, then into forward gear, and sped away.

Within seconds, one of her younger brothers suffered serious injuries, including a skull fracture.

Her younger sister, 13-year-old Isabella Cortes, was dead.

Cortes’ account of that summer afternoon was read Wednesday in Norwalk Superior Court on the opening day of the murder trial of Jose Elias Aguilar, a 30-year-old Los Angeles man who had listened to her testimony and that of her parents. He faces 19 counts, including murder, 10 counts of auto theft, five counts of kidnapping for the purpose of auto theft, two counts of attempted kidnapping during the commission of auto theft and assault on a child in connection with four auto theft incidents on July 2 and July 5, 2020.

Aguilar was accused of stealing the Cortes’ minivan on July 5. He then crashed another vehicle at the corner of Whittier and Rosemead Boulevard, then stole a second car with two passengers inside and then drove it into a bridge, authorities said.

Video shows the moment when Aguilar first walked past the minivan on the sidewalk, then turned around and walked to the driver’s door.

Prosecutor Robert Villa said in his opening statement that street vendors near the crash site held Aguilar until Los Angeles County officials could arrive and take him into custody.

Alexia Cortes testified that after the van was stolen, she tried to flag down passing motorists and ask for help. Her 10-year-old brother was also able to escape, but Isabella and her 8-year-old brother were still in the van. When none of the cars stopped, she ran inside and called out to her parents, who ran out of the supermarket with others.

Further down the street they saw the 8-year-old boy. He was still standing, but was injured, relatives said.

Further down, they saw Isabella next to a fire hydrant. Alexia said Isabella was bleeding and someone had already covered her with a blanket.

“I tried to get to her, but a lady stopped me and said I wasn’t allowed to see her,” Alexia said tearfully.

Paramedics soon arrived, her mother Kenia Gonzalez said.

“I asked them to help her,” she said tearfully. “They told me she was already dead and there was nothing more they could do for her.”

Villa told the jury of seven men and five women in his opening statement that the 8-year-old boy jumped from the moving car and that Isabella Cortes either tried to jump or was thrown from the car due to Aguilar’s erratic driving. He told the jury that she slipped on the sidewalk before hitting the fire hydrant head first.