Buses followed by more buses flowed into the south end of Brownsville on Friday.

This is part of the crowd control now underway as federal, state and municipal authorities are working the area.

"As mayor pro-tempore, I signed a disaster declaration," Nurith Galonsky Pizana said at a press conference on Friday afternoon.

Along the levee, mostly families are arriving and turning themselves in.

"It's a migrant influx. Many of them are Venezuelan nationals," Border Patrol Rio Grande Valley Sector Chief Gloria Chavez said.

Chavez says that the number of people crossing grew from 1,000 two weeks ago to 15,000 now.

Venezuelans and others are being staged at the city-owned Brownsville Memorial Golf Course after they crossed the border and were detained.

"Many of them are applying to the CBP One app at the port of entry, but at the same time are being frustrated because they're waiting to get their court date and get their process under way," Chavez said.

Chavez says at this rate, Border Patrol is apprehending 2,500 people a day in this area.

Many of those buses coming in and out are taking the migrants to detention centers in Laredo and Del Rio sectors. 

Chavez says the Rio Grande Valley has capacity for 4,000.

"Today we have overcapacity. We are at about 7,500 in holding, and we continue to receive people crossing illegally," Chavez said. "We're continuing to decompress as quickly as possible."

Border Patrol is working to control the crowds and process this large number of people.