Pinal County Sheriff Mark Lamb’s 22-year-old son and infant granddaughter  died in the Friday afternoon crash in Gilbert, police said.

“It is with heartfelt sadness to report the identity of the 22-year-old male in yesterday's fatal collision on Elliot and Cole to be that of Cooper Lamb, Pinal County Sheriff Mark Lamb's son, and his infant grandchild— both passengers of the vehicle,” the Gilbert Police Department stated in a release Saturday afternoon.

The Pinal County Sheriff's Office posted:

"Last night, Sheriff Lamb lost his son, Cooper Lamb, along with his one-year-old granddaughter in a crash in Gilbert. Cooper and his daughter were passengers in the vehicle. Cooper’s fiancé and mother of the child was also seriously injured. She remains in critical condition."

The crash occurred about 3:45 p.m. Friday, Dec. 16, when a truck traveling westbound on Elliot struck a car headed eastbound on Elliot as it attempted to make a left turn to go north on Cole, according to a release.

The man and infant, passengers in the car, were pronounced dead at the scene, and the woman driver of the car was taken to a hospital with life-threatening injuries.

Police said Saturday the driver of the truck, which appeared to be traveling at normal speed, was not injured but after an investigation was arrested for possible impairment.

Gilbert Police Department’s traffic reconstruction team is part of an ongoing investigation, authorities said. Elliot was closed between Recker and Kenneth until shortly after midnight for the investigation.

Gilbert police Saturday emphasized that with the holidays here drivers should take extra care and allow sufficient time to reach their destinations.

“Many of the collisions, especially during the holidays, are avoidable,” police said in a release.