Two girls were seriously injured in a stabbing attack while making their way to school in Germany on Monday morning, authorities said. The students—aged 13 and 14—were attacked in the early hours in the southwestern town of Illerkirchberg. Local police said the pair were probably heading to a bus in a neighboring community to attend high school when the assault began at around 7:30 a.m. German newspaper Bild reports that the alleged knifeman ran into an apartment building, which was later stormed by law enforcement. The suspect has been arrested—it’s unclear if he was known to the girls, and a motive for the crime has yet to be determined.