A jail fire killed eight inmates who could not be rescued because the guard had left with the keys, Brazilian police said Wednesday.

Officers had to enter a neighboring house and break through the jail's wall to free 14 surviving inmates Tuesday night in Rio Piracicaba, a town of 14,000 without a fire brigade, Minas Gerais state police said.

The officers "did not have the keys to open the cells," according to the police statement.

An unidentified relative of one of the inmates told Globo TV that "the jail guard left with the keys."

The New Year's Day fire likely began when a lamp short-circuited and ignited mattresses. Some inmates squeezed into the cell's bathroom, but others were apparently asphyxiated, police said.