Brussels, AP—A three-nation investigation led to one of the biggest seizures of synthetic drugs in Europe, a haul of products to create Ecstasy pills with a street value of EUR 1.3 billion (USD 1.75 billion), the Belgian prosecutor’s office said Friday.

After 30 raids in Belgium, the Netherlands and Poland, 11 people were under arrest charged with possession, production and trading in drugs as part of a criminal gang, it said.

“It is the biggest such bust ever in Belgium and one of the largest in Europe,” Wenke Roggen, spokeswoman for the federal prosecutor’s office, said. “It is quite incredible.”

Products seized included about 1,000 kilograms of MDMA and 18.5 tons of Ecstasy precursor safrole, Roggen said. The criminal organization was made up of people with Belgian, Polish and Turkish nationality, she said.

Most of the products were discovered in a suburban Brussels garage and in southern farmland around the city of Chimay, where men in biohazard suits were still working on the cleanup operation on Friday. Products were also found at an undisclosed location in the Netherlands.

“It is a shock that our region was at the center of such an important production of illegal products,” Chimay mayor Francoise Fassieux said.

Authorities had to evacuate some people around the area of the plant where the drugs were produced, Fassieux said.