DENVER -- A sport utility vehicle carrying a family of five struck a tow truck on Interstate 70 Tuesday afternoon, killing a 3-year-old child and injuring four others.

The Chevrolet Suburban had clipped a flatbed tow truck on its left rear corner and flipped several times before it landed upside down on the guardrail, Denver police said.

The crash occurred just before 4 p.m. on the shoulder of the westbound lanes of I-70, just before Sheridan Boulevard. Traffic was shut down at I-70 between Washington and Sheridan to allow emergency workers to remove the injured and detectives to piece together the cause of the crash.

Witnesses, shaken up by what they saw, told 7NEWS that the SUV was weaving in and out of lanes at high speeds just before the crash. The toddler was ejected from the vehicle and died immediately.

Other drivers stopped after witnessing the violent impact and helped pull three other children out of the vehicles.

"There were a number of us that pulled pocketknives out to cut straps to extract some kids and there were people that were holding siblings and comforting them," said witness Steve Sides. "There's been a lot of prayer here today and that prayer is for a baby whose passed on and for a family who is about to go through some really tough times."

The kids, ranging in age from less than 1 years old up to 13 years old, were taken to the hospital. The female driver, believed to be their mother, was also taken to Denver Health. Their conditions have not been released.

Westbound traffic was jammed back to past I-25 and motorists were advised to avoid the area and find alternate routes west.

The tow truck involved was parked on the on the right shoulder assisting another motorist. No one in the tow truck was hurt.

That 4-mile stretch of I-70, adjacent to the Willis Case Golf Course, is expected to remain closed until 7 p.m.