Crews are working to shore up an unstable Watergate complex parking garage following a "pancake collapse" before they can continue recovery efforts, D.C. Mayor Muriel Bowser said Friday.
Three stories of the garage collapsed during construction around 10 a.m. Friday, injuring two workers and crushing at least one vehicle. A D.C. firefighters' union called the incident a "pancake collapse."
Bowser said a cadaver dog made "a possible hit" in the garage, but did not elaborate further.
News4's Mark Segraves reports that two construction workers feared missing were later accounted for. However, because it is a public garage, officials say that it was impossible to immediately know whether anyone else may have been inside.
"Earlier, as part of the response, three dogs that are trained to search for human activity found no evidence of human activity on any of the three levels," Bowser said shortly after 4 p.m. Friday. "A cadaver dog was also sent into the scene, and that dog made a possible hit on one of the three levels."
Bowser said the operation has shifted from search and rescue to recovery.
A D.C. Fire official said the garage had a "significant structural collapse."
Upon arrival, crews searched from two sides and then determined that the structure was unsafe. They worked two and a half hours to clear the most obvious areas, but crews have not been able to get fully inside the collapsed structure due to instability.
First responders are working with engingeers and construction workers to stabilize the structure, which may take until Saturday.
Once the structure is safe, rescue teams will again use dogs to search the rubble. The D.C. Fire & EMS Department's only search dog was deployed to Nepal to help in the aftermath of the earthquake there, so Montgomery County Fire & Rescue sent their dogs to aid at the Watergate.
Two construction workers were injured in the collapse, said a D.C. Fire spokesman. One worker was taken to a hospital with a minor injury. The other refused transport.
The area of the garage that collapsed was under construction at the time.
"I was installing a panel," worker Gabriel Gresczyk told NBC News, his voice still shaking. "I was looking out and I heard a rumble, and a 40-foot-by-40-foot section of earth just went down, hitting the floor below it, and then that floor went down."
"One of our guys had just come up from that area, using one of the restrooms down there," he said. "Thank God he's all right."
The Watergate complex was evacuated shortly after the incident. Residents and office workers were initially told the problem was a water main break. The hotel portion has been undergoing renovations, which were expected to be completed this summer.
"We saw smoke coming from where the hotel is being built," said resident Dave Lilling. "...We saw the construction workers leave very quickly, and then the smoke dissipated. There was an announcement on the loudspeaker system which said, 'Hey, there's been a water main break and some building issues in B3.' They advised everybody not to go down there."
Condominiums above the site have not yet been cleared for occupancy.
Many vehicles remain in the garage. Bowser said D.C. Fire officials will let drivers know when they can pick up those vehicles.
Police and fire officials said they didn't know yet what caused the collapse.
Stay with News4 and NBCWashington.com for more as this story develops.