A controlled demolition in Stamford forced the partial shutdown of a major city road Wednesday after two floors inside of the building collapsed unexpectedly.

The collapse happened Tuesday during a controlled demolition of one of the St. John Towers on Washington Boulevard.

Crews say that they noticed the 17-story building was crumbling from within on the seventh and eighth floors. The contractor says the building began coming down in ways they didn't expect.

City officials say Washington Boulevard will remain closed from Tresser Boulevard to Bell Street until the demolition is done. They say demolition has been moved to Friday evening.

Mayor David Martin tells News 12 that he knows this is an inconvenience, but public safety comes first.

Officials also say additional concerns Tuesday night caused Tresser Boulevard to also shut down, but it reopened before the morning commute.

News 12 was told at no point was the tower at risk for a total collapse, and no one had to be evacuated.

"If it does collapse, it would go inward... it wouldn't cause any problems to any of the residents in the area but it could cause problems to the roadway because debris could fly out," says Stamford police Lt. Diedrich Hohn.

The son of the original HUD consultant for the St. John Towers in the 1960s says it is bittersweet to see one of the towers be demolished.

"I affectionately refer to the three towers as my dad's other three kids," says Noel Cooke.

Police say most people have been understanding while the demolition caused backups.

Extra police officers have been stationed at nearby intersections to help with the flow of traffic. News 12 was told the timing of traffic lights has also been modified.

The other two St. John Towers will remain affordable housing apartments across the street.