Prince George’s County rescue crews worked feverishly Friday clearing debris at a Cheverly warehouse where a roof collapsed, leaving a worker missing and believed buried beneath several stories of boxes, papers and building materials, authorities said.

Mark Brady, a spokesman for the fire department, said workers would treat their job as a “rescue mission” until they found the man or his body. Even optimistically, though, Brady said that would not happen until late Friday or early Saturday after crews spent several hours removing massive piles of debris at the document warehouse, located in the 1500 block of Cabin Branch Drive.

“We’ve seen rescues in earthquake areas days after the event occurred,” Brady said. “By keeping that belief, it keeps our troops motivated.”

On Friday, the extensive search effort was hampered by sweltering 100-degree weather and the sheer magnitude of the collapse.

Brady said that the warehouse, used by a document-management company known as Recall, contained boxes of papers stacked on shelves nearly 50 feet tall and running 100 yards long or more. When someone accidentally ran a forklift into one of those shelves about 10 p.m. Thursday, it started a “domino effect” of collapse, he said.

Shelves hit other shelves, then the support beam for the roof, Brady said. When the walls started to buckle, about 12 to 16 workers were able to evacuate, but one person remained unaccounted for, Brady said.

Employees said that just moments before the collapse, they spotted their co-worker alone in an area now filled with so much debris that “it’s humanly impossible to access,” Brady said. He said that the man’s car was found in the parking lot and that the man’s wife showed up at the scene because she had been unable to reach him.

Brady declined to identify the worker but said he is about 40 or 50 years old, lives in the D.C. area and has extended family in Virginia and North Carolina. Some family members posted about the incident on social media, but efforts by a Washington Post reporter to reach them and others were unsuccessful.

Maureen O’Connor, a spokeswoman for the Maryland Department of Labor, Licensing and Regulation, said that Maryland Occupational Safety and Health investigators were looking into the incident but that she could not answer questions about it.

In a brief e-mail statement, a Recall spokesman said, “Our top priority is the safety and well-being of our employees and Recall is working closely with the rescue crews and the owner of the leased building to locate the employee and determine the cause.”

An official with the Michael Companies, which is identified on signs as owning the facility, did not return a phone message seeking comment.

In the hours after the collapse, rescue crews tried yelling for the man, calling his cellphone and even bringing in search-and-rescue dogs to track his scent, Brady said.

When those efforts failed, they hoped to dismantle part of a wall of the warehouse, thinking that would let them bring in heavy equipment to remove the piles of debris, he said.

That plan, though, was deemed unsafe, Brady said. Engineers and rescuers instead opted to tackle the debris in chunks, methodically working their way toward “Aisle 6,” where the worker was last seen.

Brady said that contractors were expected to arrive late Friday with equipment to reach up and over the wall and clear a path to Aisle 6, a process expected to last a few hours. After that, Brady said, crews would begin removing debris believed to be on top of the worker, which could take several more hours. Once enough debris is cleared, he said, rescue workers would again use dogs to try to find the man’s scent.

Brady said that the man’s wife had secluded herself at the scene. Prince George’s County Council Chairman Andrea Harrison (D-Springdale), who escorted her to the fire department’s operations center, said the woman was “not interested in speaking with anyone, other than someone who can give her information and just make sure she can keep her family informed.”

“She wants him to know that she’s out here waiting on him,” Harrison said.

Magda Jean-Louis contributed to this report.