GILBERT, Ariz. (WFLA) — An Arizona sheriff lost his son and 1-year-old granddaughter in a Friday car crash, according to officials.

Police in Gilbert, Arizona, said the crash happened after 4 p.m. when a truck collided with the side of a car containing the family of 22-year-old Cooper Lamb, son of Pinal County Sheriff Mark Lamb.

Both Cooper Lamb and his daughter were pronounced dead at the scene. The Pinal County Sheriff’s Office said the 22-year-old’s fiance was seriously injured and remained in critical condition.

“Please keep the families in your prayers and respect their privacy at this time,” the sheriff’s office said on social media.

NBC affiliate KPNX said the truck driver was not hurt in the crash but was arrested for possible impairment, according to police.