A crane hauling an air conditioner into the top floor of a 30-story building dropped the heavy load Sunday morning, smashing parts of the building and injuring 10 people.

Workers were loading the shipping container-sized machine into 261 Madison Ave. when a rigging strap holding the air conditioner broke, a city official familiar with the ongoing investigation told the Daily News.

The chiller sheered the building as it fell. Debris rained down on Madison Ave. around E. 38th St.

Part of the 30-story building's facade near the roof was bashed open.

Mayor de Blasio said the 10 injured were “primarily pedestrians” and that they were not seriously hurt.

Police were blocking traffic between 34th and 42nd Streets and Park and Fifth Aves. De Blasio said authorities hoped to have the area completely open to traffic by the Monday rush.

De Blasio, like many of the first responders and witnesses, was grateful no one was killed.

“Thank God this occurs at this hour, on a weekend, when there were not many people around,” de Blasio said at the scene.

"Obviously, this is a very serious incident. There will be a full investigation," he said.

Two construction workers were taken to Bellevue Hospital. The remaining injured were being treated at NYU Medical Center, authorities said.

Holly Moore, 51, said she and her friend were riding bikes on Madison Ave. when the debris fell.