After a maintenance worker fell to his death inside an empty water tower in Lower Providence Township on Wednesday, a second worker was left dangling by his safety harness - more than 40 feet off the ground - for more than three hours.

That man was finally removed from the 80-foot-tall aqua tower after a dramatic rescue that involved dozens of emergency personnel and a firefighter who climbed into the tower with a safety rope.

Neither the deceased man, whose body was removed from the base of the tower, nor his colleague, who was taken to a local hospital, was identified.

Nor were officials exactly sure what had caused the accident in Montgomery County.

They said three men had been performing a maintenance operation for the last two days inside the water tower on Featherbed Road. The U.S. Occupational Safety and Health Administration was investigating.

The workers' employer, Corrosion Control Corp. of Pedricktown, N.J., had been contracted for maintenance work by Audubon Water Co.

Corrosion Control has an OSHA history, said Joanna P. Hawkins, deputy regional director for the U.S. Department of Labor in its Philadelphia office. In 2008, an employee who had been sandblasting at a Philadelphia location died and OSHA assessed an $18,000 fine, records show.

Unlike this instance, however, the worker at the Philadelphia site was not wearing a harness.

A company representative did not return calls for comment.

The tower had been drained of water while the men were working.

Lower Providence Fire Chief Bryan McFarland said one man was at ground level in the tower and two others were higher when their equipment apparently malfunctioned about 11 a.m.

One man plunged to his death and the second was left dangling several stories up. The worker on the ground called 911.

Emergency personnel received reports at 11:04, said Police Chief Francis Carroll, and quickly called for help from neighboring jurisdictions.

"Here was a lot of teamwork," said McFarland. "These are out-of-the-ordinary events."

First, McFarland said, fire departments had to devise a game plan, then figure out how to reach the trapped man.

With a crane platform stationed near the top of the tower, the firefighter, from Norristown, lowered himself through an opening at the top of the water tower. It took him nearly 40 minutes to get the trapped worker to safety.

Emergency personnel, McFarland said, needed to take their time to ensure that nothing went wrong. Because the trapped man was conscious and upright, McFarland said, rescue workers had some leeway.

"Obviously, when you are in a work harness for that length of time," he said, "that's not a healthy position."

The firefighter pulled the workman to the rescue rope, and the two slowly worked their way to the bottom, where several firefighters waited for them.

Emergency personnel removed the trapped man through a manhole-like opening at ground level. He was transported by stretcher into a waiting ambulance at 2:25 p.m. and taken to Paoli Hospital, 31/2 hours after the accident. His condition was not known.

The deceased man was identified by coworkers, but his name has not been released, said Montgomery County Coroner Walter I. Hofman. He said an autopsy would be performed Thursday morning.