City officials said a contractor's drill breached the tunnel's roof after first passing through 50 feet of water and another 50 feet of soil. 

"A drilling contractor, who was performing investigative work related to the design of the upcoming U.N. Esplanade Project … accidentally perforated a small amount in the outside edge of the Queens-Midtown Tunnel," said Josh Kraus, executive vice president and chief infrastructure officer of the New York City Economic Development Corporation.

The timing could not have been worse in a city notorious for congestion getting into, out of —  and traversing through — Manhattan: the US Open, America’s premier professional tennis competition, was in full swing at Flushing Meadows-Corona Park in the Borough of Queens.  

While New York City Mayor Eric Adams was quoted describing it as “a small leak,” according to CBS, it took several hours before the MTA could finally install a temporary plug. The north tube reopened in both directions shortly after 3 p.m., and the south tube reopened around 5:45 p.m.

However, the effects were felt for hours after, with traffic snarled well into the middle of the evening commute. The MTA said no one was injured or vehicles damaged, that a permanent fix would not impact traffic, and that the tunnel was safe to pass through.

One man interviewed trying to find another way to the borough’s LaGuardia airport — as cars backed up on both sides of the tunnel — summed up the sentiment of many New Yorkers. 

"I had to walk over here because it's just been a real s*** storm over here," Kevin Santucci told CBS News. "This is insane; he didn't know he was drilling into the wall of the tunnel?"

The Queens-Midtown Tunnel opened in 1940 and stretches from Hunters Point in Long Island City, Queens, to the Murray Hill neighborhood of Manhattan. Each tunnel tube features two lanes and is more than 7,400 feet long — roughly 1.4 miles. 

The MTA says roughly 90,000 vehicles use the Queens-Midtown Tunnel each weekday.