The U.S. Border Patrol is holding asylum seekers in a "transitional" camp under the Paso Del Norte Port of Entry bridge.
A Border Patrol spokesman says the camp is meant to "keep the migrants out of the elements" while they are transported to another facility to be processed.
The group of migrants, estimated to be in the hundreds, will not be processed at the camp, the spokesman said.
The Trump administration says it will temporarily reassign several hundred border inspectors as beleaguered forces already stationed along the U.S.-Mexico border struggle to keep pace with the number of migrant families who are turning themselves in to agents to request asylum.

Hundreds of migrants are being held beneath the Paso del Norte International Bridge in El Paso, Texas. Source: AP
The move follows the Border Patrol's unusual decision to close all highway checkpoints in its El Paso, Texas, sector, which stretches across New Mexico and much of West Texas.
Arrests along the Mexican border jumped to 66,450 in February, up 149 percent from a year earlier.
Arrests in the Border Patrol's El Paso sector, which stretches across New Mexico and much of West Texas, were about eight times higher than they were a year ago.