NEW YORK, Oct. 6 (Xinhua) -- Seventeen people, including four children and one firefighter, were injured in a gas explosion at a Harlem apartment building in New York City Saturday afternoon, fire officials said.

    All the four children had burn injuries, one was in critical condition and the three others were in serious condition, said New York Fire Department Commissioner Nicholas Scoppetta.

    The firefighter was injured when debris fell on him as he entered the first floor of the building which has 20 apartments.

    The explosion rocked the five-story apartment building near Marcus Garvey Park at about 4 p.m. (2000 GMT), according to firefighters at the scene.

    Although the blast was still under investigation, Scoppetta said the blast was apparently caused by a gas leak. However, officials from New York power utility Con Edison said there was no gas odor in the area.

    Some of the building's walls were blown out and residents of the apartment building as well as nearby buildings were evacuated.

    Mayor Michael Bloomberg also arrived at the scene to inspect the damages. Building inspectors will examine the buildings to determine their structural integrity.