A worker died yesterday when he fell from the roof of the Pennsylvanian apartment building Downtown, plunging 13 stories and striking the sidewalk.

The Allegheny County medical examiner's office identified the victim as Roy Pfoertner, 53, of New Kensington.

The accident occurred at 11:01 a.m. as Mr. Pfoertner and a foreman were pulling cables to the roof, according to Diane Richard, a spokeswoman for the Pittsburgh Police Bureau. The foreman told police he heard a "thump" and turned to see his co-worker on a sloped ledge several feet below the roof. The momentum of the fall carried Mr. Pfoertner off the ledge and to the ground.

The men were not wearing harnesses because they were working only on the roof of the Romanesque building, the foreman, who was not identified, told police.

Police and representatives of the federal Occupational Safety and Health Administration are investigating.

U.S. Postal worker Martin Luterman said he heard a sound and he looked up. The worker's body already was on the walkway next to the building's side parking lot, near Liberty Avenue and the Amtrak train station entrance.

"When you got close you could see he was mangled and bleeding," Mr. Luterman said.

He and the parking lot attendant called 911.

Kelly Whitmer, property manager for the Pennsylvanian, said Mr. Pfoertner was part of a crew doing masonry work on the roof. The crew was in the final day of the project.

"It's such a tragic accident," Ms. Whitmer said.

She expressed her sympathies to Mr. Pfoertner's family and friends.

The man had worked for the contractor, Mariani and Richards, for about 10 years. The company, which is based in Castle Shannon and specializes in masonry and restoration work, declined comment.

There have been 11 construction fatalities in southwestern Pennsylvania since October of last year. In just the last week, four workers have died after falling, according to Leni Fortson, an OSHA spokesperson in Philadelphia.

On Saturday morning, 29-year-old Carl Beck of Butler fell more than 40 feet from a roof in North Strabane, Washington County. The other victims were Gary E. Dwire, 56, who fell from a house in New Kensington, and Michael Grinder, 40, who fell two stories at a site in Monessen. Both accidents occurred on Friday morning.

About 8 percent of all work-related deaths stem from falls, U.S. Department of Labor statistics show.

Ms. Fortson said OSHA has six months to investigate an incident.

In 2006, the agency issued a $3,000 fine to Mariani and Richards after the death of 44-year-old James Neely, who was killed when an elevator struck his head on a Downtown construction site.

The general contractor on the site, Massaro Corp., received a $63,000 fine.