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WELD COUNTY, Colo. — Two people were killed and several others were injured in a four-vehicle crash on Friday morning, the Colorado State Patrol said.

The crash happened near the intersection of Highway 52 and Weld County Road 41, between Fort Lupton and Hudson.

Sheila Sinclair, 29 of Lochbuie, and her 6-year-old son Jackson Sinclair died in the crash, the Colorado State Patrol said.

Investigators said neither of them were wearing seat belts. The woman’s two younger daughters were hospitalized Saturday.

Randal McIrvin of Keenesburg was in another vehicle and he was in the hospital with life-threatening injuries. Investigators said he wasn’t wearing a seat belt.

One car was carrying a family, including an adult woman and three young children.

There were no reported injuries from the people in the other two vehicles involved in the crash.

A passerby attempted CPR until first responders arrived on the scene.

Three hospitals were involved in caring for the injured, including Platte Valley, St. Anthony’s and Children’s Hospital Colorado.

Highway 52 was closed between Weld County Roads 37 and 41 through the morning for the investigation.

It’s not known if weather or speed were involved in the crash, though heavy fog made for low visibility in the area.

The cause of the crash is under investigation.