WASHINGTON (AP) — US Border Patrol agents on horseback engaged in “unnecessary use of force” against non-threatening Haitian immigrants but didn’t whip any with their reins “intentionally or otherwise,” according to a federal investigation of chaotic scenes along the Texas-Mexico border last fall that sparked widespread condemnation.

In a 511-page report released Friday, Customs and Border Protection (CBP) blamed a “lack of command control and communication” for mounted agents using their horses to forcibly block and move migrants during an influx of Haitians arriving last September at the US border outside Del Rio, Texas.

“We’re gonna learn from this incident and we’ll find a way to do better,” CBP Commissioner Chris Magnus said during a news conference announcing the report. “Not everyone’s going to like all the findings but the investigation was comprehensive and fair.”

Video and photos of the incident made it appear agents were whipping Haitians, which caused outrage among advocacy groups and civil rights leaders. The Biden administration promised a full investigation after many in the president’s own party objected that such tactics with racial overtones were the kinds of policies the US was supposed to be moving away from after years of hardline immigration tactics under President Donald Trump.

A former police chief, Magnus took over the nation’s largest law enforcement agency in December and is being watched closely for shepherding the ongoing investigation. Homeland Security Secretary Alejandro Mayorkas said in a statement Friday that “the organisational failures of policy, procedures, and training that the investigation identified were a disservice to the agents and the public they serve.”

Last fall, Biden called images of what occurred “horrible” and “outrageous.”

“I promise you, those people will pay,” the president said then. “There is an investigation underway right now and there will be consequences.”

Asked if the politically charged environment marred the investigation, Magnus said “it was inevitable, certainly not surprising, that there was going to be a reaction to that from the community, from those in the media from elected officials, from different advocacy groups.”

But he said he instructed investigators “that all of these things were to be put aside, to be disregarded.”

“I was counting on them to do a fair, thorough, comprehensive investigation with no attention to this outside influence,” Magnus said.

By September 19, 2021, around 15,000 Haitian migrants had crossed from Mexico into the United States and were concentrated in an encampment underneath the international bridge.

Magnus said the investigation began the day after the incident and included testimony from more than 30 people, among them witnesses and journalists. Investigators said they were unable to locate Haitian migrants involved to get their accounts — but used statements and court documents that some provided as part of lawsuits they filed against US authorities.

Magnus said four Border Patrol personnel have been recommended for disciplinary action for their conduct, though he declined to discuss exactly what each had done to warrant possible punishment, or elaborate on what sanctions they could face. That comes after prosecutors in April declined to pursue criminal charges, he said.