Alert plainclothes officers spotted 27-year-old Karon Agurs unzip a fannypack on the platform at the Brooklyn Bridge - City Hall station just after 2:45 a.m. Thursday.
They approached him and asked what was in the pack.
He told them it was a gun. A struggle for the weapon ensued, and the gun dropped to the platform.
Police finally got Agurs under control and took him into custody. They recovered the weapon, which turned out to be a ghost gun.
They also found three fully loaded magazines, nine fully loaded high-capacity magazines and extra hollow point bullets.
In all, more than 300 rounds of ammunition were recovered.
Agurs was charged with criminal possession of a loaded weapon and criminal possession of a weapon.
"This kind of smart and alert patrolling by the NYPD is a key reason why we wanted more officers in the subway system and why crime has dropped dramatically since the spring," MTA Chief Safety and Security Officer Patrick Warren said. "This arrest makes our customers and transit workers safer."
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