A 5-year-old boy died after he was attacked by the family's pit bull dog Monday in Oro Grande, the San Bernardino County Sheriff's Department said.

The attack took place in the 15100 block of Portland Street around 2:57 p.m., the department said.

The boy was with an adult family member and there was no known reason why the dog attacked the child, Sgt. Jeff Allison of the SB County Sheriff's Department said.

"Unfortunately, the child did not survive," Allison said.

The dog was quarantined by Animal Control and the child's parents have been notified, authorities said.

Detectives from the Victor Valley sheriff's station were investigating the death and interviewing the family, Allison said.