TARRYTOWN, N.Y. (CBSNewYork) – The final span of the Gov. Mario M. Cuomo Bridge was slated to open to drivers Saturday, but has been delayed because of safety concerns.

“In continued disassembly of the old Tappan Zee Bridge last night, a potentially dangerous situation developed where a piece of the old bridge has become destabilized and could fall,” the New York Thruway Authority said in a statement. “Given its proximity to the new completed span, out of an abundance of caution, motorists will remain in the current traffic configuration until a thorough evaluation by Tappan Zee Constructors is complete. The second span is finished and ready to open to traffic as soon as the Thruway Authority is assured there is no risk to the new span.”

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The U.S. Coast Guard said an inspection found that a span of the old Tappan Zee Bridge had become “destabilized and could fall.”

On Friday, Gov. Andrew Cuomo was joined by former Secretary of State Hillary Clinton for a ribbon-cutting ceremony to mark the grand opening of the south span. 

The north span opened last October, replacing the Tappan Zee.

“As the situation on the old Tappan Zee Bridge unfolds Rockland County is working closely with our counterparts at the State to ensure our utmost concern is addressed – the safety of residents in Rockland and throughout the Hudson Valley region. Last night, assets from the Office of Fire and Emergency Services and the Sheriff’s Department responded to the old bridge to help suspend river traffic and evaluate the situation. We will continue to offer the use of our resources to New York State for the duration of this situation and stay in close communication,” Rockland County Executive Ed Day said in a statement Saturday.

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The projected has been surrounded by controversy since the governor named it after his late father and former New York governor, Mario Cuomo. The New York state Senate and Assembly have introduced bills to rename it the “Governor Mario M. Cuomo Tappan Zee Bridge,” and thousands of people signed a petition to keep the old name.

“Safety has to come above all else, and the Governor needs to be fully transparent about what happened here. A ribbon cutting ceremony should not have been held if the bridge span was not yet safe,” Democratic gubernatorial challenger Cynthia Nixon said in a statement. “There are real, reasonable questions about whether this bridge span opening was accelerated to aid the Governor’s campaign. Governor Cuomo needs to answer those questions swiftly, and allow for an expedited FOIL process. There must also be an investigation.”

“The closing of the second span of the new Tappan Zee Bridge due to safety concerns, just hours after its opening, is shocking. It’s now clearer than ever that the bridge was opened to meet Governor Cuomo’s political timetable without regard to public safety,” said Republican candidate Marc Molinaro. “Our first priority must be the safety of motorists and to ensure that the entirety of the new bridge is safe and that deconstruction of the old span can be completed without danger.”

“Westchester County Police became aware of the situation with the old Tappan Zee structure late Friday night,” Westchester County Executive George Latimer said. “The County immediately stepped into action, and the County Police Marine Unit was deployed to help  stop river traffic from going near the old structure.  We continue to work closely with State officials, and are in constant conversation with engineers on the scene.  The safety of Westchester County residents, and all travelers, is our top priority.   Any further inquiries should be directed to the New York State Thruway Authority.”

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Engineers were being flown in from across the country to assess the situation Sunday morning. The governor’s office did not immediately provide a timeframe for when the final span would be opened to traffic.