13 deaths reported in Southern California mountains since snowstorm, only 1 so far ruled weather-related

Thirteen people have died after powerful storms hit Southern California's San Bernardino County and cut off mountain communities. However, only one of those deaths, which was caused by a traffic accident, is so far being considered weather-related, according to the San Bernardino County Sheriff's Department.

"The preliminary information in the other deaths does not indicate they are weather-related, but those investigations are ongoing," the sheriff's department said.

A series of snowstorms brought unprecedented snow to California from late February into early March. San Bernardino County declared a local emergency on Feb. 27 "after residents of mountain communities found themselves trapped at home or unable to reach home due to several feet of snow that fell over the weekend," officials said at the time.

The sheriff's department provided more details Thursday about some of the victims.

Four of the victims were either in hospice or died in the hospital, while the remaining eight deaths are under investigation.

"Many of the deceased had significant medical histories or chronic conditions," the office said in a statement.

One of the victims was a 39-year-old woman who was struck by a vehicle in Fawnskin on Feb. 26, according to the sheriff's office. Two days later, a 65-year-old woman was found dead in her home in Wrightwood, the sheriff's office said.

On March 2, a 77-year-old woman was found dead in her Crestline home by her landlord, the sheriff's office said. A day later, a 77-year-old man was found dead in his home in the Valley of Enchantment during a welfare check requested by his family, according to the sheriff's office.

A 33-year-old man was also found dead on March 3 inside his Arrowbear home, the sheriff's office said. A 62-year-old man was found dead in his Big Bear City home the same day, according to the sheriff's office.

On March 6, a 42-year-old woman was found dead in her Big Bear Lake home following a welfare check, and a 96-year-old woman was found dead by a neighbor in her Crestline home, the sheriff's office said.

On March 8, a 68-year-old man was found dead in his Crestline home, according to the sheriff's office.

On Feb. 23, the National Weather Service issued a blizzard warning for the San Bernardino Mountains, the first in more than three decades. The weather service initially forecast a snowfall of about 5 feet at elevations as low as 5,000 feet.

Crews have removed more than 7.2 million cubic yards of snow from highways in San Bernardino County, which equals nearly 2,270 Olympic-size swimming pools, according to the governor's office.

"We continue to support our allied agencies who made great progress overnight on utility restoration. Last night deputies responded to several well checks; residents were safe, supplied, & declined evacuation. Deputies continue responding to calls & assisting residents," the sheriff's department said Wednesday.

Residents have told horror stories about being stuck, and snowed in at homes with no way in or out.

Christine Foster, who lives in the San Bernardino Mountains, told ABC News on Monday that she and her 76-year-old father have been hunkered down, unable to get out of their home for 14 days with food running low.

"You can't even shovel the stuff. It's just rock-hard ice. Shovels just easily break," Foster said in a telephone interview from her home in Lake Arrowhead.

The storm left about 600 elementary and middle school students from Orange County's Irvine Unified School District stranded for a weekend, after they were unable to return from a school trip.

More rain and snow are headed toward California Thursday and Friday when a major storm hits the state. An atmospheric river will slam the San Francisco area with heavy rain and dump another 5 feet of snow in the Sierra Nevada Mountains.