BERLIN, June 1 (Xinhua) -- A fire broke out overnight at a hospital in the Hohenfelde district of the northern German city of Hamburg, killing three patients and injuring more than 50 others, local authorities confirmed on Sunday.

According to the Hamburg fire department, two of the injured are in life-threatening condition, while 16 others sustained serious injuries and 36 suffered minor injuries.

The fire started in the geriatric ward on the first floor of the hospital and spread to the second floor. Firefighters were alerted to the fire shortly after midnight.

Thick smoke from the fire spread throughout every floor of the building, prompting a large-scale emergency response. Firefighters conducted rescues through open windows, and the fire was completely extinguished in the early hours of Sunday.

The cause of the fire remains under investigation. ■