New figures showed U.S. apprehensions at the southern border rose sharply, as Mexican and U.S. officials ended their first day of talks Wednesday without a deal to head off tariffs President Trump has threatened on Mexico.

“Immigration discussions at the White House with representatives of Mexico have ended for the day,” Mr. Trump wrote Wednesday evening on Twitter. “Progress is being made, but not nearly enough!” He said talks would resume Thursday.

Mexico’s foreign minister, Marcelo Ebrard, said the talks were cordial and that Mexico is “optimistic because we had a good meeting” and believes that tariffs can still be averted. He said both sides agreed that the current migration situation at the border must change.

U.S. Customs and Border Protection authorities said Wednesday they had apprehended 132,887 people at the border between official entry points in May, including a record 84,542 traveling in family groups and an additional 11,507 unaccompanied children. By the end of February, more families had been arrested in the preceding five months than in any previous 12-month period.

The May numbers mark a 34% increase from April, when the administration said it encountered just under 100,000 people who crossed the border without authorization.