Ismael “El Mayo” Zambada, one of the world’s most powerful drug lords and leader of Mexico’s Sinaloa cartel, has been arrested by US federal agents in El Paso, Texas. The 76-year-old, who co-founded the criminal organization with Joaquin “El Chapo” Guzman, was taken into custody on Thursday along with Guzman’s son, Joaquin Guzman Lopez, according to the US Justice Department.

Zambada had been charged in February by US prosecutors with conspiracy to manufacture and distribute fentanyl, a drug more potent than heroin that has been blamed for the US opioid crisis.

Details surrounding the arrests remain unclear, but it appears both men flew into the United States. The Wall Street Journal reports, citing Mexican and US officials, that Zambada was tricked into boarding a plane by a high-ranking Sinaloa member following a months-long operation by Homeland Security Investigations and the FBI. Zambada believed he was inspecting clandestine airfields in Mexico.

According to officials, Zambada was “lured” onto a private plane under “false pretenses” by Guzman Lopez. Zambada thought the plane would fly south within Mexico, but instead, it flew north and landed in El Paso, said Fox News correspondent Bryan Llenas, citing law enforcement sources. Guzman Lopez surrendered to US authorities and turned on Zambada because he “blamed Mayo for the capture of his father,” Llenas added.

In a written statement on Thursday evening, US Attorney General Merrick Garland stated that the two men lead “one of the most violent and powerful drug trafficking organizations in the world.”

“Fentanyl is the deadliest drug threat our country has ever faced, and the Justice Department will not rest until every single cartel leader, member, and associate responsible for poisoning our communities is held accountable,” Garland said.

American prosecutors assert that the Sinaloa cartel is the largest supplier of drugs to the US. Authorities have previously noted that fentanyl is the leading cause of death for Americans aged 18 to 45.