LISBON, Aug. 16 (Xinhua) -- A fire broke out early Saturday at a nursing home in northern Portugal's Mirandela, leaving six people dead, five seriously injured, and 20 others with minor injuries, local authorities said.

The incident, which happened around 5 a.m. local time (0400 GMT), was confirmed by Luis Carlos Soares, commander of the Mirandela fire department, in a statement sent to local broadcaster RTP.

Aderito Gomes, one of the board members of the institution, said the blaze is believed to have started in connection with an anti-bedsore mattress in a room with three residents, all of whom died. Three other elderly persons died due to smoke inhalation and respiratory complications.

The nursing home hosted about 90 elderly people. After the incident, some of them were transferred to hospitals in Mirandela, Macedo de Cavaleiros and Braganca, while the rest are being relocated to other facilities.

Authorities stressed that the fire was not connected to the ongoing wave of wildfires affecting several parts of the country. Enditem