Joshua Petersen is accused of shooting his five month old boy, Ryker Peterson. The incident happened at a home near 500 North and 500 East around 1 p.m. on Friday.
Sergeant Gregg Ludlow with American Fork Police said Petersen turned the rifle on himself, but a family member stopped him before he could pull the trigger.
The boy was immediately taken to American Fork Hospital then flown to Primary Children's Medical Center where he died.
Friends of the Petersen family said they are in shock by the tragic incident.
Petersen is in the Utah County Jail facing an aggravated murder charge.