SAN JOSE (KPIX 5) – A Southwest passenger breaking an FAA regulation Wednesday afternoon may have led to an emergency landing at Mineta San Jose International Airport, according to authorities.

The Southwest flight out of San Francisco bound for Los Angeles diverted to San Jose after reports of a fire on board.

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Airport officials said Southwest Flight 1250 from San Francisco to LAX made a U-turn over King City and flew to San Jose over concerns about a possible fire. The flight landed safely at 4:10 p.m.

The plane taxied to a gate without incident.

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The San Jose Fire Department later confirmed the entire incident may have been caused by a passenger who was allegedly smoking in the lavatory.

The smoke in the bathroom may have sent smoke into the cabin, leading to the fire worries.

Smoking on an airplane is — of course — illegal and could lead to criminal charges. Southwest later confirmed the customer in question was turned over to local authorities.

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No one was injured and no flights were delayed at the airport because of the emergency.