VANCOUVER -- The last thing Paramjit Masutta did before she died was push her twin daughters to safety.

The 48-year-old mother was walking with her girls in Surrey, B.C. on Tuesday when a runaway delivery van suddenly veered in their direction.

At the last moment, Masutta, who had been holding her daughters' hands, managed to push the girls out of the way. By all accounts, she saved their lives.

"I would expect that," said Masutta's brother-in-law, Daljit Banga. "Paramjit was a beautiful mother, she was always very protective of the children."

Grieving relatives returned to the scene on Wednesday, including the victim's eight-year-old daughters. The family said the girls are struggling to accept what happened, still wanting to believe their mom will be coming home.

"They still have that thought, but one of the girls just saw the flowers and it really broke her down," Banga said.

Firefighters and paramedics tried to resuscitate Masutta, but were unable to save her life. She would have turned 49 on Christmas Eve.

Surrey RCMP are still investigating how the delivery van ended up rolling down the hill on 144 Street without anyone behind the wheel. It's unclear whether the vehicle was left in neutral.

"Certainly they will be looking to see exactly what the driver's actions were and what they were doing immediately before and during the incident," Cpl. Joanie Sidhu said.

The vehicle struck at least one other car before jumping the sidewalk near 61A Avenue.

The driver, a contractor hired by Amazon, has been co-operating with the RCMP's investigation. Police said he is devastated by what happened.

Amazon released an emailed statement to CTV News late on Tuesday saying the company is also "working with law enforcement and the delivery service partner as they investigate.”

“Our thoughts and deepest sympathies are with the family and loved ones during this difficult time,” said spokesperson Owen Torres.

Surrey RCMP are appealing for witnesses, particularly any drivers who may have dash cam video from the area around the time of the crash, as they try to piece together the events that led to Masutta's tragic death.

With files from CTV News Vancouver's Ben Miljure