A fire erupted at a hospital in the Brazilian city of Rio de Janeiro, leaving at least 11 people dead and forcing medical staff and desperate relatives to rescue patients from smoke-filled wards.Hospital authorities said the blaze on Thursday evening was thought to have been caused by a short circuit in a generator, although the city mayor said sabotage could not be ruled out.Firefighters battled the blaze at the private Badim hospital, near Rio's iconic Maracana World Cup football stadium, for several hours before extinguishing it.Hospital director Fabio Santoro said on Friday that 11 deaths had been confirmed and that searches were still underway for one patient who had been reported missing. Emergency personnel searched through the burned-out building until the early hours of Friday to recover bodies.The hospital said there had been 103 patients in the building when the fire broke out and that "more than 100 doctors were mobilised to bring help to the victims." Seventy-seven of them had been moved to other hospitals, while 14 had been cleared to return to their homes.During the evacuation, patients on gurneys and stretchers were carried into surrounding streets as ambulances struggled through crowds of curious onlookers to transport patients to other medical facilities."The doctor arrived in the room and told us that there was fire and that we had to evacuate as quickly as possible," 58-year-old Teresa Dias, who was visiting her father, told AFP."They put him on a wheelchair and tied him up to prevent him from falling out. There were a lot of other sick people on stretchers on the stairs."Staff wheeled medical equipment outside, and the most seriously ill patients were taken at first to a nearby children's nursery.Sheets tied together were seen hanging from hospital windows.'Smoke spread very quickly'"I was able to take my mother out of her room and when we got to the fire escape, there were a lot of people running around," lawyer Carlos Otorelo, whose 93-year-old mother is being treated for pneumonia, told the UOL news website. "It was terrible because the smoke spread very quickly."Other relatives were forced to wait outside for word on their loved ones as dense black fumes filled the sky."I heard the loud noise of glass breaking and thought it was shooting or a robbery when I heard screaming. I went downstairs to see what was happening and I saw a lot of smoke," said local resident Terezinha Machado, 76.Hospital authorities said smoke spread to all floors of the building, and pointed to a generator in the oldest part of the complex as the probable cause of the fire.Mayor Marcelo Crivella said investigators would probe whether the fire was an accident."Experts will have to find whether anyone was responsible. I hope I am wrong, but we have to check there was no sabotage, we have to investigate," he told reporters when visiting the hospital Friday.The fire service said the premises had safety certificates.Rio has been hit by two major fires in the past year, including when the National Museum was gutted by flames last September, destroying most of its priceless collections.In February, 10 teenage members of the Flamengo football club were killed in the prefabricated building where they were staying. Faulty air conditioning systems were the cause of both fires.