Berlin police say two young children were seriously wounded in a knife attack Wednesday at a school in the south of Germany’s capital, and a 39-year-old suspect was detained.

The girls, ages 7 and 8, were flown to a hospital. One of them had life-threatening injuries, according to a Berlin police statement.

Mayor Kai Wegner said that he was shocked by what he described as an “incomprehensible deed.”

“My thoughts in these difficult hours are with the two wounded girls,” he said. “I wish them a speedy and good recovery.”

Wegner expressed his sympathy to the parents, teachers and fellow pupils of the victims, and said he was in close contact with police about the attack.

Berlin’s state education department said authorities don’t have any indication that there was a political or religious motive behind the attack.