At least four people are dead and 10 are injured after a 15-story tall crane came crashing down on the city?s East Side.

The owner of the crane is Reliance Construction Group, a Parsippany-based company. Owner Stephen Kaplan is calling what happened a freak accident.

The accident occurred just after 2 p.m. Saturday afternoon. The crane plummeted at least 20 stories, demolishing one building and damaging another three. The four people who were killed are all believed to be construction workers.

Firefighters spent the afternoon removing the dead and searching for living. Rescuers were picking through debris Saturday night ? using police dogs and imaging cameras ? to prevent further collapse.

N.Y.?s Mayor Bloomberg called the accident one of the worst construction accidents in city history. ?Construction is a dangerous thing,? Bloomberg says. ?We don't know why this happened, we will do an investigation, we will find out why this happened."

Kapling says workers were raising the crane when a falling piece of steel sheared one of the ties holding it to the building. The company says a sub-contractor had been hired to operate the crane.

The crane was part of a construction project to build a 46-story $110 million high rise condo.

The American Red Cross has set up shelter at a nearby high school for residents forced out of the buildings.