The blaze engulfed the Domicil retirement home in Offenbach, close to Frankfurt-am-Main, on Monday morning, local mediaoutlets said. Fire brigades were scrambled at around 3.40am local time, and arrived at the scene to deal with the emergency.
One man was found dead inside his room on the second floor of the building, while 24 others were injured in the fire. A total of 10 people were seriously injured by smoke, and were taken to nearby hospitals for trauma care.
Hessenschau newspaper reported that criminal investigators have arrived at the scene, seeking to establish the cause of the fire. Officers had previously cordoned off the adjacent streets, telling residents of Offenbach, a city of 137,000 residents, to avoid the area.