A building in the 400 block of K Street Northwest is seen during a collapse on Friday. (Bill O'Leary/The Washington Post)

One building completely collapsed and two others, including an adult club, were damaged Friday afternoon near Mount Vernon Square, injuring one person and snarling rush-hour traffic as firefighters investigated and searched the debris.

Authorities called in search and rescue teams from Montgomery County but said it was as a precaution. Officials said they do not believe anyone was trapped in the rubble. It was not clear how the one person was hurt; police said the injuries appeared minor.

Police shut K Street from Fourth to Seventh streets, a heavily trafficked thoroughfare between Massachusetts and New York avenues near I-395. Several buildings were evacuated, including a paint store in an adjacent block, a nail salon and the Cloakroom Gentleman's Club in the 400 block of K Street NW. The club’s entrance was littered with debris and entertainers in light attire mixed with bystanders outside.

“Everybody, fortunately, is okay,” said Kam Ali, one of the club’s managers. “The building is damaged. It’s pretty serious.”

A cause was not immediately known, but authorities noted the week’s heavy rainfall and said the back part of the three-story club at Fifth and K streets appeared to be undergoing expansion.

Tim Wilson, a spokesman for the D.C. fire department, said the initial investigation shows that the back part of the club’s building collapsed onto a three-story building next door, causing the roof to fall into the basement. Debris from the three-story building fell onto a two-story structure next door, causing its second floor to collapse. The smaller building was boarded and had a for-sale sign in front.

The facades of the two heavily damaged buildings were still standing Friday evening, though the interiors “are gone,” Wilson said. He said building inspectors will be examining the structural integrity of other buildings on the block. New construction is booming in the area, with apartment buildings towering over the older large rowhouses occupied by the club and nail salon.