NEW YORK ( CNN ) -- Twenty-four people , including eight children , were injured in an apparent gas explosion at a Harlem apartment building , the New York Fire Department said . The explosion blew out some of the windows in the five-story building . John Rodgers , a spokesman for New York-Presbyterian Hospital , said Sunday that four of the eight children were from the same family . The conditions of all those injured were not immediately known . One child was in critical condition and the three others were in serious condition , New York Fire Department Commissioner Nicholas Scoppetta said . All four had burn injuries . One of the injured is an infant . A firefighter was also injured , but was in stable condition Saturday evening . He apparently was struck by falling debris , Scoppetta said . About 200 firefighters responded to the scene of the blast on West 119th Street in Harlem . New York Mayor Michael Bloomberg visited the five-floor building after the explosion . The 4 p.m . ET blast blew some of the building 's windows out , according to firefighters . Watch rescue workers tend to injured » Although the blast was still under investigation , Scoppetta said the cause appeared to be a gas leak . New York police said the blast was at the rear of the structure . Residents who assisted in pulling the injured out of the building said some kind of restaurant was being operated on the bottom floor of the building . Scoppetta refused comment on those reports , citing the ongoing investigation . An emergency room worker at Harlem Hospital Center said the facility received five to six people from the explosion about 4:30 p.m. , but would not provide an update on their conditions . The building , which has 20 apartments , was evacuated , as were apartment buildings on both sides , Scoppetta said . Building inspectors will examine them to determine their structural integrity . E-mail to a friend . CNN 's Caleb Silver , Jim Acosta and Richard Davis contributed to this report .
NEW : Four of the eight injured children came from same family , hospital says . One child in critical condition , three in serious condition with burn injuries . About 200 firefighters were at the scene in Harlem . Residents say some sort of restaurant was being operated in bottom of building .