Imagine being stranded on the 69th floor of the nation’s tallest skyscraper. That’s exactly what happened to two window washers on Wednesday when they became stranded outside the 69th floor of the 1 World Trade Center, NBC News reports.

To rescue the stranded workers, firefighters reportedly cut a rectangle through several layers of glass, then pulled the two window washers into the interior of the building after attaching an extra safety harness to each of them.

“It was a fairly straightforward operation,” NYFD Battalion Chief Joseph Jardin, who supervised the rescue, told The Associated Press.

“And, of course, they were 68 stories up,” he added. “That presented a little bit more of a challenge.”

Although the cause of the incident is still under investigation, window-washing company Upgrade Services identified a possible cause in a statement released shortly after the rescue.

“The cause of the incident appears to be equipment failure of the traction hoist brake mechanism that supports one side of the rig,” the company wrote. “This caused the scaffold to drift into an almost vertical position, leaving our men stranded until a rescue could be performed.”

The two window washers were taken to a hospital for observation and released.

Photo credit: @NYFD