County firefighters responded to the home at 22800 Vista Grande Way around 8 a.m. A witness called 911 after seeing debris falling from the hillside, which is located right above a shopping center.
When firefighters arrived, they discovered a 40-foot-wide slide area about 10 feet deep right below the home's patio.
"The cause was discovered by the initial arriving units from County Fire," said San Bernardino County Fire Capt. John Lansing. "They found out that the water line underneath the patio had broken and caused saturation of the hillside, causing the collapse. They quickly secured the water to the residents."
The house has since been red-tagged. A red-tag designation condemns the property as not suitable for habitation. There are concerns that the house could slide since a portion of the house's patio and retaining wall have already collapsed.
San Bernardino Fire Department's Urban Search and Rescue personnel were also called out to inspect the home. Officials said they found significant cracks along the patio and inside the home. The homeowners were evacuated.
"Kind of shocked us, so we had to grab whatever we could, left the house until we got a call that we could retrieve" some belongings, Dr. Arthur Jimenez said.
Jimenez, who bought the home 15 years ago in part because of the sweeping view, is hoping he'll be able to save it.
"The best scenario is that we can just build a retaining wall, fill up the whole patio, stabilize it and we can proceed with our lives," Jimenez said.
Jimenez said his home owner's insurance will likely not cover the damage.
Officials say no other homes in the immediate area are threatened. There are no neighboring evacuations in place.