A massive drill bit nearly hit an F train packed with about 800 riders Thursday when it busted into a train tunnel, according to the MTA.

The drill bit, 10 inches in diameter, pierced the subway tunnel from the street as the Queens-bound F train rolled out of the 21st Street station in Long Island City around 11:45 a.m. The equipment scraped the train's roof and down the side; there were no injuries to riders or major damage to the train, according to spokesman Kevin Ortiz.

The near-miss occurred as a subcontractor, Griffin Dewatering New England, was working on the the East Side Access project, which will bring the Long Island Railroad to Grand Central Terminal. The company could not be reached for comment.

Riders walked back to the 21st Street station platform through another train that pulled up from behind. Queens-bound F trains were rerouted to run along the 53rd Street tube until 5:30 p.m., while Manhattan service was normal.