A fire broke out at a major hospital in Hamburg, Germany, overnight, killing at least three people, the local police said on Sunday.

The fire at the Marien Hospital was confirmed by a spokesman for the Hamburg Police early Sunday morning. He said he was unable to confirm other details.

Some local news media outlets reported that more than 50 other people were injured, two of them critically. The cause of the fire was not immediately clear.

The hospital treats over 90,000 patients a year, according to its website. Hamburg is Germany’s second-largest city.

This is a developing story.