Federal authorities raided a sprawling ranch in Oklahoma and a prominent quarter horse race track in New Mexico Tuesday, part of an investigation that a published report said was connected to a horse breeding operation run by the brother of a high-ranking operative in a Mexican drug cartel.

Ruidoso Downs, New Mexico, Police Chief Doug Babcock said FBI agents raided the track Tuesday morning to serve an arrest warrant. Dozens of federal agents had taken over the stables wearing bulletproof vests and were collecting evidence. At least two horses were seen being led away from the stables.

In Oklahoma, an FBI spokesman confirmed that a ranch in Lexington, about 40 miles (64 kilometers) south of Oklahoma City, was raided, but he did not discuss details. At least a half-dozen agents wearing fatigues and baseball caps emblazoned with FBI were still at the ranch early in the afternoon, but declined to comment. The spokesman, Clayton Simmonds, said he couldn’t elaborate because arrest, search and seizure warrants were sealed.

“We are executing warrants in the Lexington area in reference to an ongoing law enforcement investigation,” said Simmonds.