CHICAGO (CBS) — A young woman was shot and killed in front of her twin sister and her two nieces Wednesday night, after a carjacker jumped into their parked car while they were trick-or-treating in the Belmont Cragin neighborhood.

Police said two women and two children were sitting in a parked BMW near Long and Belden avenues around 9:30 p.m., when a man jumped into the vehicle. The gunman forced the driver to take him several blocks to Belden and Lawler, near Blackhawk Park, before he shot and killed the passenger.

The victim, 21-year-old Maira Coronel, was shot twice in the head. She was pronounced dead at the scene.

Coronel’s mother said she was trick-or-treating with her twin sister and her two nieces — ages 1 and 2 — when they were carjacked. Her family said the shooter stuck a gun in her back and demanded her money and cell phone; she gave him $40 in cash, but refused to give up her cell phone.

That’s when he shot her twice in the back of the head.

“She was a kind person. She would never do anything to anybody. Yeah, a lovely person,” said her sister, Leticia Coronel. “We just want to know if somebody sees something, to let us know, and the police.”

The shooter was described only as a masked man wearing all black. He was last seen running away near Blackhawk Park. Police said he got away with an unknown amount of cash from the victim.

It was not immediately clear if the children were related to the victim, or if they live in the neighborhood.

No one was in custody Thursday morning. Area North detectives were investigating.

Police said investigators were trying to determine if there was any surveillance video in the area that could help identify the gunman.