German police watch refugees sitting outside a migrants shelter in Calden, where clashes erupted Sunday among hundreds of occupants. Getty Images

More than a dozen people were reportedly wounded Sunday when a series of fights broke out among hundreds of refugees in a shelter in Calden, Germany. Police in the central German city spent hours trying to calm several groups of refugees after they began brawling at a canteen around lunchtime, Deutsche Welle reported. The fight then escalated, pitting Albanians and Pakistanis against one another, and ended Sunday night when about 70 migrants faced off with 300 others. No arrests were made.

The center at the former Kassel-Calden airport is housing about 1,500 people from 20 nations, many of them fleeing violence in their home countries. German officials have said they expect to see up to 1 million refugees seeking asylum in the country, though they noted they can't accept everyone. "Our hearts are wide open, but our capabilities are finite," President Joachim Gauck said Sunday.

The clashes in Calden reportedly started after a disagreement between a young refugee and an older migrant. This ignited already high tensions, leading police to use tear gas in an effort to control the situation, the Daily Express reported. At least one group of refugees was forced to move to a different location as a result, BBC News reported.

Sunday's brawls weren't the first in the region among migrants in Germany. In Leipzig last week, about 200 people fought each other when an Afghan boy reportedly threatened a Syrian girl with a knife, according to the Telegraph. In Suhl in August, about 15 people were injured in a conflict when an Afghan man tore pages out of a Koran holy book.

News of the fights fueled the debate about whether refugees should be separated by religion, which German politician Hans-Peter Friedrich has reportedly called "sad but obviously necessary."