The Latest on the large numbers of immigrants at the southern border(all times local):

6:40 p.m.

Border officials in Texas say a group of 116 Africans was arrested Thursday after wading through the Rio Grande to enter the United States.

The migrants were from Angola, Cameroon and other African nations and include families with children and young people who were not with relatives.

This was the first large group that agents in the Del Rio sector have arrested, although big groups have been showing up every day in other areas of the southern border. Agents have encountered 182 large groups, or those with more than 100 people, since October.

It’s unclear if the migrants in Texas were seeking asylum, and the agency is still processing them.

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2:12 p.m.

U.S. authorities are overstretched and overwhelmed by an unprecedented surge of Central American families arriving at the southern border.

It is against that backdrop that President Donald Trump threatened this week to slap tariffs on goods from Mexico unless it cracks down on the flow of migrants.

On Wednesday, for example, Border Patrol agents near downtown El Paso, Texas, encountered a group of 1,036 migrants who had entered the country illegally — the biggest cluster the agency has ever seen.

At one point in May, a government holding cell designed for 35 migrants was crammed with 155.

And six children have died in U.S. custody since September, three in the past month.