New York, Dec 30 (IANS): The fire that ripped through an apartment building here, killing 12 people, appears to have been caused by a youngster who was playing with a stove, New York's mayor has said.

"What we think at this point is that it unfortunately emanated from an accident, a young child playing with a stove on the first floor of the building," Bill de Blasio said on Friday during his weekly radio show on WNYC, Efe news reported.

The blaze at the five-storey building in the Bronx began at around 6.50 p.m. on Thursday and spread rapidly.

De Blasio said the toll could rise.

"We've lost 12 people. We could lose more. There are some still fighting for their lives," the mayor said of what he had earlier described as "the worst fire tragedy we have seen in this city in a quarter century."

Four children were among the victims, the youngest just a year old.

"Our hearts go out to every family who lost a loved one here and everyone fighting for their lives," fire commissioner Daniel Nigro said.

More than 160 firefighters battled the flames, according to the Fire Department of New York.

Questions arose about possible shortcomings in fire-safety measures at the building, which was built more than a century ago, but De Blasio said that authorities had found no evidence of a problem.

"It does not appear that there was anything problematic about the building or the fire safety in the building. It seems like a horrible, tragic accident," he said.