Peruvian authorities arrested eight people in connection with a cocaine ring that allegedly shipped drugs on planes from Lima’s international airport by switching passenger luggage with identical bags containing the substance, counter-narcotics police said Thursday.

In April and May, five police officers assigned to the airport were arrested for alleged cocaine smuggling. That was followed by the arrests of eight airport services employees through Wednesday. The employees were also allegedly involved in the ring.

The ring would switch bags filled with cocaine with passengers’ luggage, which was put on later flights.

The arrests announced Thursday were made following a tip from Mexican police, which led to Peruvian authorities finding a suitcase with about 50 pounds of cocaine on a LAN Airlines fight, Gen. Vicente Romero told Associated Press.

The eight airport services employees who were arrested worked for three different companies, including Transber SAC, which loads cargo. One of the suspects had $58,000 in cash on his person when arrested and allegedly told authorities he made $7,000 per shipment. But counter-narcotics police are still unsure how long the ring operated.

According to the U.S. Drug Enforcement Administration, Peru overtook Colombia in 2012 as the world’s biggest cocaine producer.