An A321 with around 160 passengers on board bound for Los Angeles was taxiing to the runway at JFK airport, when the pilots lost communication with the ATC at around 8:00 PM on Tuesday, due to radio problems. Around 15 minutes later, they managed to re-gain communications, but the hijacking protocols couldn’t be reversed at that point. Heavily armed FBI agents stormed the plane. After about 1.5 hours, the plane was cleared and returned to the gate for inspection.
The pilots likely intended to squawk 7600, but accidentally squawked 7500 instead. This must’ve been very scary for the passengers, who were then later placed on a different flight to Los Angeles.
For eyewitness accounts, I recommend reading the DailyMail article.