European police have swooped on a continent-wide gang that smuggled millions of prescription medication pills to countries like Finland and Norway, the EU’s judicial agency said on Friday.

Forty-seven suspects were arrested and more than 6 million pills seized in the operation conducted by Estonian, Finnish, Romanian and Serbian police, Eurojust said in a news release.

“The criminal group, which operated throughout Europe, bought pills from other criminal networks in Serbia,” the Hague-based law agency said in a statement.

“The pills, used to treat anxiety, seizures and insomnia, were then hidden in tires, in cars, which were transported on lorries, and in clothing, to be taken to Romania,” it said.

They were then smuggled to Estonia and other countries including Finland and Norway, where gang members “acted as distributors and sold the pills on the streets.”

The pills seized had an estimated street value of $13.6 million, Eurojust said.

The arrests were made under a large police operation Thursday coordinated by Eurojust and Europol. Some 61 addresses were searched simultaneously in Romania, Serbia and Finland.

Police also confiscated guns, mobile phones and luxury cars in the operation, Eurojust said.

A Europol report on criminal networks released in April said the majority of Europe’s most dangerous gangs now focused on drug smuggling, mainly dealing in cocaine, cannabis, heroin and synthetic drugs. Europol said that cartels, mafias and gangs throughout Europe have been using fruit companies, hotels and other legal businesses as fronts to carry out their operations.

Last month, Europol and Eurojust said they successfully dismantled an encrypted communication platform that was established to facilitate criminal activity. The platform, known as Ghost, was used for “large-scale drug trafficking, money laundering, instances of extreme violence and other forms of serious and organized crime,” Europol said.

In July, Spanish police announced a Europol-backed takedown of a major network transporting Latin American cocaine into Europe by boat in an international operation involving 50 arrests across eight countries. Europol released a video showing authorities opening bricks of cocaine on one of the ships as well as officers raiding properties, making arrests, and finding drugs, cash and firearms.