LOS ANGELES — More U.S. homes are entering the foreclosure process, setting the stage for a surge in properties repossessed by lenders this year.

The number of homes getting first-time foreclosure notices rose 7 percent in March from February, foreclosure-listing firm RealtyTrac said Thursday.

The trend was more pronounced in the Puget Sound region: First-time foreclosure notices in March rose 70 percent in King County from the previous month, according to RealtyTrac data. Pierce County saw only a 7 percent increase, while notices fell 28 percent in Snohomish County.

Bank repossessions, however, slowed in the region last month. They were down from the previous month by 13 percent in King County and 25 percent in Pierce County, RealtyTrac's data show. But in Snohomish County, they were up by 23 percent.

Nationally, it marked the third consecutive monthly increase in activity and reflects stepped-up efforts by banks to take action against homeowners behind on mortgage payments.

"We're not out of the woods yet with foreclosures," said Daren Blomquist, a vice president at RealtyTrac. "There are more batches of foreclosures coming through the pipeline."

Thirty-one states posted a monthly increase in homes with a first-time foreclosure notice. Nevada led the pack with an increase of 153 percent.

Even so, foreclosure activity overall — as measured by the number of properties receiving a notice of default, scheduled for auction or repossessed by lenders — sank in March to the lowest level since July 2007, the firm said.

Banks took back 55,075 homes in March, down 14 percent from the previous month, and down 25 percent from March 2011.

RealtyTrac expects banks will repossess close to 1 million homes this year. Last year, lenders took back 804,000 homes.

Seattle Times business reporter Sanjay Bhatt contributed to this story.