A Colorado State Patrol trooper was hit and killed on Interstate 70 in eastern Colorado late Friday night while working a single-vehicle rollover crash that severely injured a woman and an 18-month-old child, according to the Arapahoe County Sheriff's Office.

Trooper William Moden, 37, was struck and killed while assisting with the crash, which reportedly resulted from speeds of more than 100 mph, according to witnesses.

The car, driven by a 22-year-old woman and carrying an 18-month-old child, left the highway and rolled multiple times, about 200 yards across a field, according to Arapahoe County Sheriff's spokeswoman Deborah Sherman. The woman and the toddler were ejected from the vehicle, the Denver Channel reports.

Trooper Moden was on foot at the crash scene when he was struck by a passing vehicle just before 9:45 p.m., the State Patrol said. The driver of that vehicle stopped. An investigation is underway.