Five members of the regional music group Grupo Fugitivo were found murdered after being kidnapped in Reynosa, a city near the U.S.-Mexico border, authorities in Mexico confirmed.
The musicians, aged between 20 and 40, were abducted on May 25 while traveling to perform at a private event.
Shortly after, their families reportedly received ransom demands. Mexican authorities say the motive behind the killings remains under investigation.
Nine alleged members of the Gulf Cartel have been arrested in connection with the murders, according to Tamaulipas state attorney general Irving Barrios Mojica.
Officials also seized nine firearms and two vehicles during the operation.
Grupo Fugitivo was known for performing regional Mexican music, including corridos, a style that has at times glorified drug traffickers.
It is unclear whether the band was targeted due to their musical content or if they were victims of broader cartel violence in the region.
Reynosa, located in the violence-plagued state of Tamaulipas, has long been a stronghold of the Gulf Cartel.
The U.S. government has labeled the cartel a global terrorist organization and issued its highest-level travel advisory for the area, citing rampant crime, kidnappings, and armed clashes.
The U.S. State Department warns that criminal groups frequently operate with impunity in northern Tamaulipas, with limited ability for local law enforcement to intervene.
