Violence against Syrian asylum seekers spiked over the weekend with police Sunday reporting three different attacks in which six Syrian refugees had to be treated for injuries in the hospital.

Two of the attacks, in Wismar and Magdeburg, were committed by groups of more than 20 persons who harassed and beat asylum seekers with baseball bats on Saturday.

Police in nearby Rostock said in a statement Sunday two Syrian men, who were not identified, were standing outside their shelter in Wismar on the Baltic Sea on Saturday night when a group of 20 persons approached them and started beating the refugees. The attackers fled and the two asylum seekers had to be taken to the hospital to be treated for injuries.

In Magdeburg, 30 persons beat up two 26-year-olds and one 35-year-old Syrian man, who also had to be treated in the hospital. Police detained one 24-year-old suspect.

In a third attack, a 26-year-old Syrian man was injured by pieces of glass when explosives were thrown against the window of his room in an asylum shelter in Freital in the eastern state of Saxony. The interior minister of Saxony, Markus Ulbig, sharply condemned the "cowardly and cold-blooded attack" and said a far-right motive was likely, the German news agency dpa reported.

In Sehnde near Hannover, a 43-year-old man was detained for allegedly committing an arson attack on a home of an asylum seeker family from Montenegro early Sunday. Nobody was harmed in the attack.

Several arson attacks were also reported on designated future asylum shelters across Germany, among them an empty hotel in Dresden and a former youth club in Castrop-Rauxel in western Germany.

Attacks against asylum-seekers and migrant shelters have increased sharply in Germany in recent months as refugees surge into Europe seeking to escape war and poverty and start a new life.

Germany's interior ministry said last week that there had been 576 crimes against refugee shelters this year so far, compared to 198 in all of the last year.