It has left Parchim's small Muslim community shaken. About 150 Muslims live in the town of 19,000 people.
The community is so small it does not have a purpose-built mosque, but holds its prayers in a disused transformer station. There is no minaret, and no call to prayer. The makeshift mosque was under renovation at the time of the incident.
"What's next?" Dirk Flörke, the mayor of Parchim, told the local Parchimer Zeitung newspaper.
"Integration can only succeed if we all talk to each other. And we are now faced with the task of integrating the refugees."
The town's Muslim community includes both new arrivals who came with the influx of asylum-seekers last year and families who have lived in the town for 20 years. It is made up mostly of Syrians and Turkish Kurds.
Parchim lies in the state of Mecklenburg-West Pomerania, which has a history of far-Right activisim.
The state is due to hold regional elections at the weekend, with the far-Right Alternative for Germany neck-and-neck with Angela Merkel's Christian Democrats (CDU) in the polls.
The breeze blocks were removed from the mosque entrance within a few hours. Someone put up a new flyer in answer to the ones left by those who had blocked the door.
"Walls are there to be torn down," it read. "Never give up hope. Be strong and stay happy."