Dive summary:

• A construction crane at a building site in Kirov, Russia, was caught by crosswinds Sunday and managed to slip its base or somehow come loose, toppling toward another building.
• The crane's jib crashed across the roof of the building as the tower gouged a groove down the front of the structure from roof to ground, as seen in the YouTube video below.
• One witness told a news agency, RT, that the crane was on rails and moved about 100 meters on them until it hit a stop and fell over.

From the article:

Meanwhile, construction workers on the site continued to go about their duties as if nothing had happened, according to the person who filmed this video. ...