Officials are investigating after an elevator technician fell to his death at a construction site in Manhattan on Tuesday morning, police said.

The NYPD said Jucong Wu, 33, was found unconscious and unresponsive at the bottom of an elevator shaft at 111 East 24th Street just before 9 a.m.

Officials said he was working to install an elevator car on the ninth floor of the site and fell to ground level. He was pronounced dead at the scene.

Officials said he was not connected to a fall-protection safety line.

"This is dangerous work," said Gerald Matthews of the NYC and Vicinity District Council of Carpenters. "Any time you are working on a scaffold, you're working outside a building, you have to be tied off, you have to be safe. We don't know what happened here, but we are going to find out."

A stop-work order is in effect for the site.

The Department of Buildings is investigating.

Sources said that, before Tuesday, the site had no open violations or complaints.