Manhattan buildingEmergency services evacuated a Manhattan street block during the Tuesday morning rush hour after structural columns buckled inside a skyscraper undergoing construction work, officials said.The former head office of the drug giant Pfizer, near the UN headquarters, is being converted from offices into apartments in a transformation project at the tower. "Two structural columns have buckled, in addition to multiple cracks and sagging floors. The building remains unstable. Since arriving on scene, we have witnessed additional movement in one of the compromised columns," mayor Zohran Mamdani said. "This is an extremely serious situation," Mamdani said."I am grateful to report there have been no injuries at this time, and that every worker has been accounted for," he said, adding that engineers were working to develop plans to shore up the structure.Emergency struts and beams would be brought in to strengthen the building, officials said. Nearby hotels, businesses, apartments and a school were evacuated and streets were closed as a precaution as police and firefighters swarmed the area.Clifford Johnsen, a representative of the Steamfitters Local 638 union, said that the addition of new floors had put pressure on the building's supports. "I've been in construction 21 years, and I've never seen a beam bend in half - so this is super dangerous."