A group of 15-20 people wearing black clothes and hoods attacked the building housing Facebook’s offices in Hamburg, Germany, police said in a statement Saturday. Reuters reports that the vandals smashed glass, threw paint, and sprayed “Facebook dislike” on a wall. A Facebook spokesman said no one was injured.

While the motive for the attack wasn’t clear, Martin Ott, Facebook’s managing director for northern, central, and eastern Europe is being investigated for the platform’s alleged failure to remove racist hate speech, Reuters reports. Ott is based in Hamburg.

The investigation into Ott was announced last month. From Reuters, in November:

The German chancellor, Angela Merkel, urged Facebook to do more this year on the matter, while the country’s justice ministry wants to set up a taskforce with the company, other social networks and internet service providers with the aim of identifying criminal posts more quickly and taking them down.

Facebook said it would not commenting on the investigation. “But we can say that the allegations lack merit and there has been no violation of German law by Facebook or its employees,” it added.

The company earlier announced a partnership with a group called FSM, which voluntarily monitors multimedia service providers, and said it would encourage its users to push back against racism.

Three similar investigations were also announced in October, thelocal.de reported. Facebook’s European headquarters are in Ireland, a complaint filed by a lawyer, Chan-jo Jun, against the Hamburg offices alleges that advertising revenue generated there allows the site to operate in Germany.

“Facebook Germany GmbH therefore promotes the dissemination of inflammatory, criminal content through actions in Germany that start in the German business headquarters in Hamburg,” the complaint argues.

Photo via AP Images. Contact the author of this post: brendan.oconnor@gawker.com.