Riverside County sheriff's deputies said they responded to a home in the 7400 block of Carrollton Place after receiving a 911 call around 3 a.m.
The residents said they were woken up when an intruder tried to sexually assault a family member. They detained him until deputies arrived.
The suspect was identified as 18-year-old Isaac Jenkins of Eastvale. He was arrested and booked into the Robert Presley Detention Center on suspicion of burglary with intent to commit a sexual assault and first-degree burglary.