WASHINGTON — More than 1,000 migrants were apprehended after illegally crossing the border near El Paso, Texas, early Wednesday morning, according to two U.S. officials and a document obtained by NBC News.

The group of 1,036 is the largest ever encountered by the Border Patrol; the previous record of 424 was set last month.

Customs and Border Protection has noticed a trend in the number of large groups crossing the border together. In fiscal year 2018, border agents encountered 13 groups of more than 100 immigrants. Now, they have seen that same number in a single day, according to Brian Hastings, the chief law enforcement operations directorate for the U.S. Border Patrol.

President Donald Trump told reporters at the White House on Thursday that he will make his "biggest statement on the border" later in the day or on Friday.

A third U.S. official expects the large group apprehension to be a major part of his announcement.

The 1,036 immigrants included 934 people traveling in family groups, 63 children traveling alone, 39 single adults and others who had not yet been identified. All of those processed as of Wednesday morning are from the Northern Triangle countries of Central America, with 515 from Guatemala, 135 from Honduras and 76 from El Salvador.

Immigration advocates say more immigrants are traveling in large groups because they believe in "safety in numbers," as conditions along their journey are treacherous. U.S. officials say the large groups overwhelm medical teams and border agents, who are most often patrolling in pairs.

Overall numbers of undocumented immigrants crossing the border both legally, by presenting themselves at ports of entry, or illegally, by crossing between ports of entry, have skyrocketed in recent months. Both March and April saw numbers above 100,000, the highest in over 12 years.

One DHS official said the agency expects May to breach 120,000 in the number of immigrants apprehended and deemed inadmissible.