NEW YORK (AP) — A construction crane collapsed Friday on New York's Upper East Side, smashing into a 23-story apartment building as it fell to the ground, killing two construction workers and seriously injuring another.

It was the second deadly crane accident in 2½ months and the latest of several construction mishaps in the city, which recently shook up its Building Department and beefed up inspections.

"What has happened is unacceptable and intolerable. Having said that, we do not know at the moment what happened or why," Mayor Michael Bloomberg said at a news conference, adding that it appears the builders followed regulations.