German police said Monday they were hunting for a group of up to 20 people who damaged doors and windows at the company’s offices in Hamburg and wrote “Facebook Dislike” on a wall.

The unidentified group of people also threw paint bombs and damaged doors and windows at the American company's German headquarters in Hamburg's Neustadt neighborhood, according to investigators.

Police said Sunday that they are asking witnesses who know more about the group to come forward, according to The Associated Press. They said the group attacking the building Saturday night consisted of 15-20 people, who were clad in black and wore facemasks.

Police spokesman Joerg Schroeder said the motive was not clear. On the leftist Internet page Linksunten, anonymous authors said they had attacked the building to protest against Facebook's overpowering presence online.

The extent of financial damage caused by the vandalism wasn't immediately clear. It comes as the European head of Facebook is under investigation in Germany over the company’s alleged failure to remove hate speech, Reuters reports.

An investigation into the company was announced last month as German politicians and celebrities voiced concern about the rise of anti-foreigner comments in German that were being posted on Facebook pages.

The country is currently grappling with an influx of refugees flowing through its borders. German Chancellor Angela Merkel said Monday that "we want to, and will, appreciably reduce the number of refugees, because it's in everyone's interest."

A Facebook spokesperson said last month that “the allegations lack merit and there has been no violation of German law by Facebook or its employees,” according to Reuters.

The Associated Press contributed to this report.