Some residents stranded in Southern California mountain communities by a huge snowfall could be stuck for another week, an official said Friday.

A late-February blast of arctic air produced a rare blizzard east of Los Angeles in the San Bernardino Mountains, where thousands of people live at high elevations in forest communities or visit for year-round recreation.

Extraordinary snowfall buried homes and businesses, overwhelming the capability of snowplowing equipment geared toward ordinary storms.

By last weekend, all highways leading up into the mountains were closed and have opened intermittently since then to residents and convoys of trucks loaded with food or other supplies.

The estimate by San Bernardino County Sheriff Shannon Dicus was an improvement in the outlook for stranded residents, which previously ranged up to two weeks.

The sheriff and other officials said progress has been made, but they described severe conditions that, for example, have forced firefighters to reach emergency scenes such as fires in snowcats.