The Transportation Security Administration says it closed Kennedy's Terminal 7 at around 9:45 a.m. Saturday after discovering the equipment problem and realizing that people had been let through without being properly screened.
Procedures call for the entire terminal to be emptied and the passengers re-checked whenever that happens.
Some travelers posted photographs on Twitter showing the terminal lobby jammed with people waiting to get back in.
The Port Authority of New York and New Jersey says the screening checkpoints were reopened to passengers by 11:45 a.m.
The terminal is used by British Airways, United, and other airlines.
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