U.S. authorities prevented hundreds of largely Venezuelan migrants from entering the country from Mexico after a sizable group attempted to cross the border illegally but was stopped by barbed wire, barriers, and shields.

The migrants congregated at the border in Ciudad Juarez, Mexico, but were unable to enter into the United States due to difficulties getting appointments to apply for asylum via a new U.S. government app.

Many of the migrants had small children with them.

At one point, some migrants attempted to hurl an orange, plastic barrier at the U.S. line, Reuters images show. Some people said pepper spray was deployed to repel them.

“Please, we just want to get in so we can help our families,” said Camila Paz, an 18-year-old Venezuelan, sobbing heavily. “So I can have a future and help my family.”

Neither U.S. Customs and Border Protection (CBP) nor the Mexican government’s national migration authority immediately replied to requests for comment.

After some pushing and shoving with the officials, the crowd of migrants eventually withdrew, with some heading down to the banks of the Rio Grande where they were monitored by U.S. immigration officials arrayed on the other side.

Many migrants have become fed up with the asylum process since the Biden administration made an app called CBP One available to them that was meant to streamline applications.

They say the app is beset by persistent glitches and high demand, leaving them in limbo in perilous border regions.

The U.S. Department of Homeland Security has said recent app updates will simplify and speed up the process.

Describing her situation as “horrible, horrible,” Paz said she had been trying to cross the border for a month, watching her money disappear and getting no nearer to claiming asylum.

“We want answers please,” she said, “the (CBP One) application has done absolutely nothing for us.”