Horrible news, it might have been a space heater.

A raging fire gutted the top floor of a six-story Bronx apartment building on Tuesday night, killing four women and injuring another victim, officials said.

The blaze started in a sixth-floor apartment on Grand Concourse near E. Mount Eden Ave. in Mount Eden, with smoke pouring into two neighboring apartments, officials said Tuesday night.

The thick smoke killed two women in one neighboring apartment, and two more in another, police said. Witnesses said firefighters pulled all four women from the building, but all were unconscious.

One witness watched as medics frantically tried to revive one woman.

"They were pumping the chest of the woman. She wasn’t responding. She didn’t look good,” said one witness, who didn’t give his name.

One of the victims, Maribell Turner, 70, was a nurse practitioner, her grieving sister told the Daily News.