Uber's Amsterdam offices were raided by police on Tuesday, according to Yahoo! News. The raid is part of an investigation into the UberPOP app, which is currently underway in Holland.

Investigators are searching for evidence that Uber has broken Danish taxi laws. A statement from the public prosecutor's office says that documents were taken from the offices during the raid Tuesday. "Uber uses the UberPOP app to book taxi rides with drivers who do not have a permit to operate as a taxi...it is illegal to offer a taxi service without a permit," the statement said.

The investigation into Uber was announced by prosecutors this past April after the UberPOP app was banned from accepting appointments in Amsterdam. Investigators believe the app could still be in use despite this. Uber has been fined multiple times for breaking taxi laws, to the tune of 450,000 euros, according to Business Insider Australia. That's about $506,000 in U.S. dollars.

Uber has faced difficulties in other European countries as well due to taxi laws. Germany issued a nationwide ban against UberPOP last week, according to The Wall Street Journal. French police also conducted a raid on Uber's offices in Paris recently.