MADRID—Six residents of a nursing home in eastern Spain perished after a fire broke out in the night, authorities said Wednesday. Valencia’s regional head, Ximo Puig, said that 17 more residents were hospitalized, with three in serious condition. Firefighters said that they rescued 25 residents out of a total of 70 that were evacuated from the nursing home in the municipality of Moncada just north of Valencia. Firefighter chief José Basset told Spanish news agency EFE that the fire appears to have started in a bedroom on the second floor. He said that when the firefighters arrived “there was a large number of people asking for help who were trapped by the smoke.” Puig said that Spain’s Civil Guard police force were investigating the cause of the fire, but that investigators believe it could have been caused by a short-circuit in a mechanism linked to an oxygen tank. “The most …