At least 18 people injured in Hamburg train station stabbing, suspect arrested: Authorities

At least 18 people were injured, including four critically, in a stabbing attack at a train station in Germany on Friday, authorities said.

The suspect in the stabbing -- a 39-year-old woman -- has been arrested, police said.

A magistrate has ordered the suspect to be placed in a psychiatric institution, Hamburg police told ABC News on Saturday.

Four of the victims were in critical condition but are now stable, police said.

The incident occurred at a train station in Hamburg. A knife was used in the attack, police said.

The suspect has been charged with 15 counts of attempted manslaughter in conjunction with dangerous bodily harm.

Police have not publicly identified the suspect. She is believed to have acted alone, according to Hamburg police, who said they are investigating her background. Police believe she may have been in "mental distress."

"So far, we have no evidence that the woman could have acted with political motivation," Hamburg police spokesperson Florian Abbenseth told reporters. "Rather, we have findings on the basis of which we are now investigating in particular whether she may have been in a state of mental distress."

She was arrested without a permanent home on Friday evening and will now be held in a psychiatric hospital for treatment and further investigation.