A German hospital says two of the three victims it is treating for wounds inflicted during an ax-and-knife attack by an Afghan refugee are in a critical but stable condition.

The Wuerzburg university hospital said in a statement Thursday that a fourth victim, who is currently being treated at a hospital in Nuremberg, would be transferred to its hospital as well.

Four Hong Kong tourists were brutally attacked Monday night on a commuter train near Wuerzburg by a 17-year-old Afghan refugee. The attacker then wounded a woman walking her dog before he was shot and killed by police.

The Islamic State claimed responsibility for the attack and posted a video in which the teen waved a knife and referred to himself as a "soldier of the Islamic State."