Passengers on a plane traveling from San Francisco to to Paris took an unexpected side trip to Canada Monday, after an unspecified anonymous threat caused the flight to be diverted.

Air France flight 83 took off at San Francisco International Airport at around 3 p.m. local time Monday, CBS5 reports. Though the flight was supposed to a non-stop trip, it landed at Montreal-Pierre Elliott Trudeau International Airport shortly before midnight their time, after what Air France officials says was "an anonymous threat."

The Associated Press reports that about "15 fire trucks and police cars met Flight 83 at the Montreal airport, and Canadian authorities verified the aircraft, passengers and baggage."

The Boeing 777 was carrying 231 passengers and 15 crew members, Fox News reports. Upon landing, the passengers were removed slowly, and in "small groups."

"Everyone is pretty relaxed," passenger and SF resident Gilles Raymond told the AP from inside the plane Tuesday morning.

"There was no panic, no stress. Everyone is waiting in their seats. Some people are sleeping, and some are checking their phones or eating ice cream that the flight attendants gave them."

After seven hours on the ground, Air France confirmed that the threat was a false one, and travel resumed on the same plane, the Chron reports.

Seven hours later than expected, at about 9 a.m. PT, the flight landed at Charles de Gaulle.

According to a statement from Air France, "an investigation will be carried out into the origin of the threat." No further details on the nature of the threat were provided as of Tuesday morning.