DENVER — Authorities on Wednesday announced the indictments of 30 people who are accused of being members of a Denver-based drug trafficking group with suspected ties to a Mexican cartel, according to officials and court documents.

Federal agents seized a slew of drugs in the case, including about 400 pounds of methamphetamine and 15,000 fentanyl pills — a powerful synthetic opioid — that were disguised as prescription oxycodone, according to the U.S. Attorney's Office in Denver. Five pounds of heroin and four pounds of cocaine were also seized during the investigation, which began in 2018.

Twenty-five people have been arrested on drug trafficking charges in the case and five others remain at-large, including four in Mexico.

The accused leader of the group, Candelaria Vallejo-Gallo, was indicted under a charge of Continuing Criminal Enterprise, also known as the federal "drug kingpin" statute, authorities said. Vallejo-Gallo, a Mexican national, faces 20 years to life in prison.

“This is a very significant operation that took a massive amount of drugs and a large number of drug traffickers off our streets,” United States Attorney Jason R. Dunn said in a statement.

The suspected traffickers sold meth, heroin, cocaine and fentanyl pills in Colorado and transported funds from the drug sales to groups in California, and then eventually to Mexico, according an indictment in the case. Investigators believed the group was connected to a Mexican cartel, a criminal complaint said.

In a traffic stop of one suspect in January, investigators seized about 1,000 fentanyl pills that were hidden in a vent inside the vehicle, according to the complaint. More information about the case was not available on Wednesday, as some of the court documents remained sealed.

Several agencies investigated the case: The FBI, the Drug Enforcement Administration, Homeland Security, Immigration and Customs Enforcement, the IRS, the Douglas County Sheriff's Office, Colorado State Patrol, and the Aurora Police Department. The U.S. Attorney's Office in Denver is prosecuting the case.