A group of nearly 300 illegal immigrants – comprised mostly of family units and unaccompanied minors – was apprehended after crossing the U.S.-Mexico border in the Rio Grande Valley earlier this week.

U.S. Customs and Border Protection revealed Wednesday that agents working near Granjeno, Texas responded to reports of a large group of suspected illegal immigrants walking toward a river levee.

Upon arrival, agents said they found 289 illegal immigrants crossing the river levee from Mexico – making it the largest group they’ve encountered in the area so far this year.

BORDER OFFICIALS GEARING UP FOR RECORD NUMBER OF MIGRANTS TRAVELING AS FAMILIES TRY TO ENTER US

Agents said, including this group, they had detained more than 1,000 illegal immigrants in the Rio Grande Valley sector in 24 hours.

The latest large group comes as CBP has seen an uptick in such groups crossing the border illegally into the U.S.

In Arizona, agents arrested nearly 750 illegal immigrants last weekend. They all came in large groups of mostly Central American families and unaccompanied minors.

SMUGGLER USES GIRLS AS DISTRACTION TO HELP 10 PEOPLE ILLEGALLY CROSS US-MEXICO BORDER, OFFICIALS SAY

To date, in Fiscal Year 2019, the Yuma Sector in Arizona has seen a 230 percent increase in family unit apprehensions and a 36 present increase in unaccompanied minors when compared to year to date numbers last year, CBP revealed Monday.

Across the border, 60 percent of apprehensions at the border are family units and unaccompanied minors, the agency said earlier this month. More than 268,000 family units and unaccompanied minors have been apprehended at the United States’ southern border to date in Fiscal Year 2019, CBP said.

“We are currently facing a humanitarian and national security crisis along our southwest border,” CBP Commissioner Kevin K. McAleenan said in a statement earlier this month.

A senior Homeland Security official told Fox News on Monday that the government is gearing up for a record number of migrants traveling to the U.S. as families to either cross the southern border illegally or claim asylum at a port of entry this year.

The senior official told Fox News an estimated 51,000 to 58,000 people traveling as family units are projected to enter the U.S. this month, with that figure rising as high as 70,000 in May.

NEARLY 200 ILLEGAL IMMIGRANTS APPREHENDED CROSSING BORDER IN NEW MEXICO

On Monday night, at least 10 people illegally crossed into the U.S. via the California border with Mexico after a smuggler used two Salvadoran girls as decoys to distract border patrol agents.

The unidentified smuggler dropped the two girls – ages 6 and 9 – into concertina wire at an “aging” section of the border barrier, while the other illegal immigrants “got away,” CBP said.

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A video showed the girls being dropped from the wall before the smuggler fled.

Fox News' Greg Norman and Katherine Lam contributed to this report.