EL PASO, Texas (AP) — U.S. Border Patrol agents launched pepper balls at a group of migrants who crossed the U.S.-Mexico border along the Rio Grande in El Paso after the agency said one person threw a rock at one agent and another was assaulted with a flagpole.

Video captured Monday by the El Paso Times shows Border Patrol agents approaching the group, which included a man holding a very large Venezuelan flag, that had crossed the shallow river.

Border Patrol spokesperson Landon Hutchens said in a statement that as the group of Venezuelan nationals protested along the river, they tried to enter the U.S. illegally.

"One of the protesters assaulted an agent with a flag pole," Hutchens said. "A second subject threw a rock causing injury to an agent at which time agents responded by initiating crowd control measures."

Those measures included launching "less-lethal force" pepper balls, he said. He said the crowd then dispersed and returned to Mexico. Hutchens did not give details on the agents' injuries.

Before the conflict at the river Monday, a group of migrants had marched in Juarez, across the border from El Paso, demanding an opportunity to cross the border, the newspaper reported.

According to a new Biden administration policy that took effect last month, which came in response to a dramatic increase in migration from Venezuela, Venezuelans who walk or swim across the U.S. border will be immediately returned to Mexico.

The Biden administration has agreed to accept up to 24,000 Venezuelan migrants at U.S. airports while Mexico has agreed to take back Venezuelans who come to the U.S. illegally over land.

Roberto Velasco, Mexico's director for North American affairs, tweeted Monday that the Mexican government had requested information from its U.S. counterparts about the confrontation.

Jonathan Blazer, director of border strategies at the American Civil Liberties Union, called the footage "highly alarming."

"People seeking asylum on U.S. soil should be screened for protection, not pushed back, especially through use of force," Blazer said.

According to statistics from Customs and Border Protection, its officials used "less-lethal" force — such as batons, stun guns, tear gas and pepper spray — 338 times in the fiscal year that ended Sept. 30.

Hutchens said the Customs and Border Protection's Office of Professional responsibility will review Monday's incident.