The Colorado State Patrol trooper who was killed on the Interstate 70 on Friday was initially responding to a single-vehicle rollover crash in which a woman and an 18-month-old were injured, police said.

Trooper William Moden was killed while assisting in the first crash on eastbound I-70 at mile marker 324, just east of the Peoria exit, according to Arapahoe County Sheriff’s Office spokeswoman Deborah Sherman.

The Arapahoe County Sheriff’s Office as well as Adams County Sheriff’s Office deputies were called to assist in the first crash, Sherman said. Moden was struck and killed by another vehicle while working at the scene shortly before 9:45 p.m., so the Arapahoe County Sheriff’s Office took over the investigation of the single-vehicle rollover.

The woman in the first crash was allegedly driving recklessly and reaching speeds in excess of 100 mph, witnesses told police.

The vehicle had rolled over, and when police arrived at the scene, they found out that it had rolled multiple times through a field before the driver and an 18-month old baby were ejected from the vehicle, Sherman said.

Police believe alcohol may have been a contributing factor in the crash. No charges have been filed as the woman is in serious condition in the hospital, Sherman said. The sheriff’s office does not provide updates on the condition of young children.

Moden was outside his patrol vehicle at about 9:43 p.m. on I-70 near Deer Trail when another driver crashed into him. He was airlifted and pronounced dead at University of Colorado Hospital, according to Colorado State Patrol.

CSP has not released any information on the driver who crashed into Moden or the details of the crash. Officials on Sunday said they expect more information to be released to the public on Monday.

Moden, a 12-year veteran of CSP, was described as a man who always helped others, loved his job and had a sense of humor.

He’s the fifth state trooper to be killed on Colorado roads since 2015.

“It’s just another tragic, tragic loss of one of our troopers,” Sherman said.