By the beginning of the week, only a few hundred migrants had gathered under the bridge near the city of Del Rio on the border between Mexico and the United States.
Since then, the influx has increased rapidly, and on Thursday evening, more than 10,000 migrants were at the site, reports Reuters.
Growing crisis
The migrants, mostly Haitian citizens but also Cubans, Venezuelans and Nicaraguans, have crossed the US border to seek asylum.
The temporary camp has during the week developed into a growing humanitarian crisis, according to several media.
- It is chaos.
You stand there among thousands of others with your little ticket waiting for your turn, Ramses Colon, who left Cuba, told the Washington Post.
Asks for more resources
In recent days, Texas has had temperatures of almost 40 degrees and there is a shortage of both food and water for the migrants.
The US Border Police have now asked for more resources to be able to handle the situation.
"To prevent damage from the heat wave, the shaded area under the bridge acts as a temporary camp for migrants waiting to be taken care of by USBP (US Border Patrol)," a statement said.
The number of migrants from Central America and Mexico crossing the US border is more than in 20 years.
In August, more than 195,000 migrants were stopped by US authorities, according to figures from the US government.