BERLIN (AP) — The death toll in a fire that broke out in a hospital in Germany this week has risen to five, with all of the victims patients, as investigators sought to understand the cause of the blaze.

The fire broke out late Thursday at the hospital in Uelzen, southeast of Hamburg. Emergency workers arrived to flames and calls for help. They evacuated several people, and were able to stop the fire from spreading any further, according to the dpa news agency, which cited police.

Firefighters and police, some using ladders, rescued several patients from their rooms.

The German news agency dpa reported late Friday that a fifth victim succumbed to injuries, raising the earlier death toll of four to five.

Six people were seriously injured and 16 others had lesser injuries, dpa reported, citing the hospital. The injured suffered smoke inhalation and burns.

The cause of the fire was still unclear on Saturday.