The crash involves a semi truck and a silver Infinity near County Roads 49 and 54.
According to Heather Cobler with Colorado State Patrol, two adults and one juvenile in the car died on scene.
Cobler says one juvenile passenger inside the car was airlifted to Children's Hospital, where they later died.
A man inside the semi was transported to Northern Colorado Medical Center.
The crash was reported around 11 a.m. near Evans, which is south of Greeley.
9NEWS has a crew on the way. This story will be updated when new information becomes available.
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