U.S. immigration officials detained more than 5,000 migrants from Ukraine at the nation’s land, sea and air borders in March, with a significant increase in those seeking refuge at the U.S.-Mexico boundary, adding to the record influx of newcomers from Latin America and the Caribbean this year, according to U.S. Customs and Border Protection figures released Monday.

The tally — up from fewer than 1,150 the month before — marks the first official accounting of Ukrainians seeking refuge at the ports and borders since Russia’s invasion began Feb. 24. They are part of a larger group of more than 220,000 detentions on the Southwest border in March, the highest monthly total since 2000.

Many, if not most, Ukrainians have been released into the United States via humanitarian parole, which allows people to stay temporarily, and they continued arriving this month, though updated figures were not available. The Biden administration responded to the influx Monday by announcing that it would extend the eligibility of Ukrainians for “temporary protected status,” allowing them to stay here for 18 months and apply for work permits, if they arrived by April 11.