More than 10,000 immigrants are waiting in Delhi, Texas, under the bridge for access to government reception facilities, ABC News reported.

- Drinking water, towels and toilets have been provided to migrants while they await transportation elsewhere, the U.S. Customs and Border Protection has said.

To avoid health problems due to the heat, migrants have stayed under the bridge.

A large proportion of migrants are from Haiti.

Photo: San Antonio Express-News / Zuma / MVphotos

The migrants are said to have crossed the Rio Grande in a few days.

The rapidly evolving situation has been described as a humanitarian emergency and a logistical nightmare, the Washington Post says.

"We are struggling to bring in all possible resources, but this is a logistical nightmare," said Jon Anfinsen, a spokesman for the Border Guard Association.

- We move agents around the country to help, but they can't get here today and we're just trying to survive.

According to Anfinsen, priority is given to families with young children.

- Many of the agents are mothers and fathers and seeing children in a situation like this is sad for everyone.

Migrants crossing the Rio Grande on the U.S.-Mexico border.

Photo: GO NAKAMURA / Reuters

According to Del Rio Mayor Bruno Lozano, more than 10,500 immigrants had already arrived in the city.

- Although I predicted the worst case scenario, this is probably worse than the worst case scenarios, Lozano said.

Most of the migrants who arrived in Del Rio are from Haiti.

Many have lived elsewhere in Latin America since the devastating 2010 earthquake, but are now heading north.

The number of migrants surprised the authorities.

Photo: GO NAKAMURA / Reuters

More illegal border crossings have been seen at the southwestern U.S. border than in more than two decades, the New York Times reports.

More than 200,000 people crossed the border last month.

In total, more than 1.5 million border crossings have been registered this year.

The U.S. administration has planned that some of the immigrants would be flown to other border towns where their applications would be processed.

In addition, return flights to Haiti are scheduled to launch next week.