(Reuters) - The death toll from a massive mudslide that devastated a rural community in Washington state last month rose by three to 33 on Monday, with a dozen people still unaccounted for, county officials said.

A rain-soaked hillside collapsed without warning on March 22, above the north fork of the Stillaguamish River, sending a torrent of mud over the river and across state Highway 530, engulfing some three dozen homes on the outskirts of the tiny community of Oso.

Of the 33 people confirmed dead, 30 have been identified, the Snohomish County medical examiner's office said in a statement. Recovery crews were still searching for another 12 people unaccounted for as of Monday morning, but that figure could fluctuate as it has since the day of the disaster.

The dozen people still missing from the slide include three children - a 2-year-old girl and two boys, ages four and 14. At least half of the missing lived on Steelhead Drive, a street which the mudslide slammed into, the county said.

Recovery efforts have been hampered by rain creating treacherous conditions and raising the risk of further slides and flash floods.

No one has been pulled alive from the rubble since the day of the landslide, when at least eight people were injured but survived, and rescue teams have since found no signs of life.

(Reporting by Cynthia Johnston, writing by Jonathan Allen; editing by Scott Malone, Sofina Mirza-Reid and G Crosse)