A British Airways flight was delayed for hours because a mouse was spotted on the plane.
Passengers had already boarded the 10.40am flight from Heathrow to San Francisco when it was announced there was going to be a delay.
They were told they had to change planes, but were informed that it would be several hours before a gate would be available for the new plane.
A passenger told the BBC that it was announced that "a rather unusual occurrence has occurred".
Just had my flight to SFO cancelled because of a mouse on board the plane. Could it not get a visa?? #britishairways— Mark Watt (@markwatt) March 1, 2017
They then said rules stipulate that planes cannot take off if a mouse is found on board.
The passenger, called Carly, said: "I'm not sure people knew how to react. There was general disbelief."
Some passengers tweeted about the flight, with one writing a Haiku about the mouse.
Another flight was provided for the passengers four hours later.
About to fly to SF— Midland (@midlandsound) March 1, 2017
There is a mouse on the plane
We all must get off
British Airways said: "We know almost everyone wants to fly with us to San Francisco, but on this occasion there was one very small customer who we had to send back to the gate.
"Everyone with two legs is now on their way to California, and we are sorry for the delay."