None of the tanks exploded, said Assistant Fire Chief Bruce Porzelt.

No one was injured in any of the fires.

The South End fire broke out in the yard of a scrap metal business on South Avenue at 11:23 p.m.

American Medical Response medics spotted the fire from Interstate 95 and reported it, Porzelt said.

Debris in metal barrels ignited and the wind blew the flame onto a wooden overhang along the building and onto the roof, Porzelt said.

The overhang was destroyed and firefighters had to cut a hole in the roof, the assistant chief added.

The cause is under investigation, he said.

The freezing cold weather hampered firefighters' efforts because a hydrant on South Avenue was frozen, Porzelt said.

Firefighters started the evening in the South End at a home at 24 Newton St., where a stove burner accidentally left on ignited some nearby clothes shortly after 5 p.m., according to the assistant chief.

The fire spread to the stove, a washing machine and the kitchen counter before igniting the cabinets and the ceiling of the apartment.

Firefighters confined the blaze to the kitchen and the family was allowed to return to the apartment afterward, Porzelt said.

At 8:49 p.m., a cigarette tossed into a plastic garbage can in a condominium laundry room on Harmony Street ignited the can and its contents, Porzelt said.

Later, a natural gas line going to a stove was severed and the gas ignited in a second-floor rear apartment, according to Porzelt.

The fire was confined to the wall and the stove, the assistant chief said.

About 12:30 a.m. Thursday, firefighters responded to a report of smoke from a building on Dover Street, in the Upper East Side.

It was not known at press time what they found there.

Aaron Leo, who covers regional issues, can be reached at 330-6222.