The U.S. Border Patrol union is expected to challenge proposed disciplinary actions for agents seen on horseback flinging reins at Haitian migrants near the U.S border in Del Rio, Texas, in September.

Top Customs and Border Protection officials said, in a report released July 8, that the agents involved were referred for discipline and are on administrative leave after an investigation into the incident that spurred national outrage.

The agency’s internal investigative office found that the agents did not whip the migrants with the ropes as they appeared in images of the encounters circulated on social and in news media, but said there was an “unnecessary use of force.”

The migrants were crossing the Rio Grande heading back to an encampment of thousands under a border bridge with food. Border Patrol allowed the families to go back and forth for water and supplies. However, an investigative report shows that on Sept. 19, when agents and Texas Department of Public Safety officers tried to disperse the group near the river, there were “failures to make good decisions at several levels of the agency,” Customs and Border Protection said in a statement.

“Failures to maintain command and control over Horse Patrol Units, lack of appropriate policies and training, and the overall chaotic nature of the situation at Del Rio at the time contributed to the incident,” Customs and Border Protection Commissioner Chris Magnus said. “Several agents engaged in unprofessional or dangerous behavior, including one instance in which an agent used denigrating and offensive language.”

A Border Patrol agent who was captured on video yelling at a man whose family was carrying items along the river bank “acted in an unprofessional manner,” the report says.

“Hey! You use your women? This is why your country’s s—t, you use your women for this,’ ” the agent said in the video, but before he stirred the horse in the man’s direction.

The report says the officer “acted in an unsafe manner by pursuing the individual he had yelled at along the river’s edge, forcing his horse to narrowly maneuver around a small child on a slanted concrete ramp.”

The incident was referred to the U.S. Attorney’s Office for the Western District of Texas based on standard procedure. The office did not pursue charges against the agent.

“There is no justification for the actions of some of our personnel, including unprofessional and deeply offensive conduct,” Magnus said. “Unfortunately, this incident overshadowed our agents’ incredible humanitarian and law enforcement efforts in Del Rio last September.”

The images from the Rio Grande crossing sparked outrage as many commenters compared the mistreatment of the migrants to slave patrols. President Joe Biden and Vice President Kamala Harris condemned the agents’ actions and called for swift punishment. It took nearly nine months for Customs and Border Protection to complete the investigation.

The agency’s disciplinary review board has proposed sanctions for four agents. They could face unpaid suspensions to a less-severe “letter of reprimand” recording the improper conduct, officials familiar with the agency’s disciplinary process told The Texas Tribune.

The National Border Patrol Council, the border union, called Biden, Harris and Secretary of Homeland Security Alejandro Mayorkas “liars” and “spiteful humans” in a tweet Friday.

The union posted statements accusing the Biden administration of “rank hypocrisy.” Biden said the agents had “strapped” the migrants at the time. Harris compared the images to “the worst moments of our history” and slavery. Mayorkas accused the agents of weaponizing the horses to attack young migrants.

The union is demanding an apology from the administration for falsely accusing the agents of crimes that could ruin their careers, a representative said on Twitter.

“Since this administration is so deeply invested in ‘accountability’ according to Chris Magnus, it is time for Mr. Biden to be accountable and APOLOGIZE to our agents for falsely accusing them of crimes. We’ll wait.”