A building has collapsed in Manhattan and four people are injured after a report of an explosion that rattled nearby buildings and shattered windows in the area, authorities say.First responders rushed to the building on the northwest corner of 116th Street and Park Avenue in Harlem, a building of about four or five stories near Metro-North tracks. Smoke could be seen from midtown, a few miles away, and those nearby reported seeing debris floating through the air blocks away. City officials said the building is destroyed. The cause of the apparent explosion is not known. "I thought a train had exploded," said Marisa Aquino, who was at her apartment on 115th Street between Park and Lexington. "There are a ton of firefighters and a lot of smoke. Cops and first responders are everywhere." Metro-North service has been suspended out of Grand Central because of debris on tracks.