Federal investigators are trying to determine what led to the deaths of two workers killed when a piece of heavy machinery they were working in toppled near midtown Atlanta.

The Fulton County Medical Examiner's Office said the men were killed when they fell from an 80-foot lift, which had been extended to a height of 40 feet.

Emergency workers told The Atlanta Journal-Constitution the men were working on the exterior of an apartment building when the mobile lift got stuck. They say that when the workers tried to move the lift, it fell onto a concrete walkway across the street.

The men were taken to Grady Memorial Hospital and later died.

The medical examiner's office said the men were not crushed by the machine.

Tags: crane collapse