"We lost a real class act," said Lt. George Reese, who said he worked with Martinson for seven years. "This was John's life, John's love. He was always the first one to help out."

Martinson was the first firefighter to enter the 25-story building on the former site of Ebbets Field. Martinson, 40, of Staten Island was later found lying on the floor of an apartment on the 14th floor, and was taken to Kings County Hospital Center.

The fire started when a 6-year-old boy put wrapping paper on top of burners of a gas stove being used to heat the apartment, fire officials said. When the paper caught fire, the boy grabbed the burning trash and hid it underneath his bed, officials said. Neither the boy nor his mother was injured.

The city medical examiner's office said Martinson died of smoke inhalation and thermal burns.

Martinson is survived by his pregnant wife, Jessica, and their 22-month-old son, John Patrick.

Friends and colleagues remembered him yesterday as a hero and a giver, willing to help out anyone in need.

"He would give the shirt off his back for anybody," said John Castro, 38, who called Martinson a childhood friend. "I'm going to miss him."

"He was a great guy," she said. "There are no words to describe how horrible it is."

By Johathan Starkey with staff writer Steve Ritea contributing to this story.