President Trump warned Honduras on Tuesday that his administration will...

The “caravan” of migrants making their way to the US border has swelled to 4,000 people — as the number of undocumented immigrants entering the country skyrockets, according to reports.

The large cluster of Hondurans — many of whom are kids traveling with and without their parents — has split into two groups, and part of it is now approaching the Mexico-Guatemala border, NBC News reported Wednesday.

The news comes as the number of crossings at America’s southern border surges, including record levels of undocumented parents entering with their kids, according to The Washington Post.

US Border Patrol agents arrested more than 41,400 undocumented immigrants in September, up from 37,544 in August, according to NBC News.

And 16,658 of those arrested were people traveling with family — the highest number in a single month on record, The Washington Post reported, citing unpublished statistics from the Department of Homeland Security.

That’s an 80 percent increase from July, just after President Trump ended his policy of separating families at the border.

Groups of 100 or more parents and kids have been turning themselves in at the border, saying they’re too afraid to return.

“We’re getting hammered daily,” one Border Patrol agent in Texas told The Washington Post.

Trump has been receiving regular updates about the border-crossing numbers and is reportedly fuming at the figures, leading him to reconsider reinstating the separation policy.

The separations were bad for his polling numbers, but a senior DHS official said that migrants viewed its end as a “clear signal” to cross.

“Now we’re actually getting crushed,” the official said.

On Tuesday, Trump threatened to cut aid to Honduras, El Salvador and Guatemala if they don’t quell the mass migrations.

Secretary of State Mike Pompeo is headed Friday to Mexico, which has sent another 500 federal police to its southern border ahead of the caravan’s arrival, NBC News reported.