NEW YORK, July 18 (Xinhua) -- A steam pipe exploded in central Manhattan in New York Wednesday, sending plumes of steam roaring into the sky and throwing debris nearby. Authorities said it was not terrorism related.

    Blocks near the site have been evacuated and several subway lines diverted as a result of the blast. There were reports of four confirmed injuries but more injuries are feared because rocks and other debris rained down in the rush hour explosion.

    Some described the spewing steam and debris as "tornado rising from the ground."

    Fire trucks and emergency crew are working at the site, which is located near 41st Street between 3rd and Lexington avenues.

    CW 11, a local TV station, cut short of its newscast in response to request to evacuate.

    Some witnesses reported smells of sulfur and drops of yellowish matter at the scene.

    Amid reports of asbestoses in the air, people are advised to leave the area of the explosion.

    "Anyone who's in the area is potentially putting himself at risk," Andrew Troisi of the city's Office of Emergency Management told CBS news. "It's imperative that they get that message."

    Steam is pumped beneath New York City streets to heat and cool thousands of buildings, including the Empire State Building.

    In 1989, a gigantic steam explosion ripped through a street, killing three people and sending mud and debris several stories into the air.