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A lithium ion camera battery apparently caught fire and began smoking at Orlando International Airport on Friday, causing a panic that toppled stanchions, raised fears of a shooting and canceled around 24 flights, authorities said.

The airport said that a loud noise was reported at around 5 p.m. in front of a security checkpoint, and "In an abundance of caution, passengers inside the terminal were instructed to exit the building while Orlando Police and Orlando International Airport staff investigated.”

Greater Orlando International Aviation Authority CEO Phil Brown said in a letter posted online Saturday that the camera battery inside the bag apparently caught fire and began to smoke, the passenger dropped the bag and emergency responders moved it away from crowds.

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"Others hearing the luggage being dropped, stanchions falling, and rapid movement mistook the sounds as gunfire and within seconds a spontaneous evacuation of the main terminal occurred," Brown said in the letter.

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Orlando police on Twitter assured people that there was no shooting. Thousands of people were forced to go back through TSA lines, NBC affiliate WESH reported.

"This is a layover. I was actually supposed to stay on the plane and go to Newark, New Jersey. Then I heard someone panicking and I was like, 'What's going on?'" Henry Appiah told the station.

Brown said in the letter that emergency staff tried to restore calm “but as everyone is aware, a few trying to communicate a message to this large of a mass is a daunting task.” Brown said there will be a complete review of the airport response.

The Federal Aviation Administration allows lithium ion batteries under 100 watt hours in carry-on luggage, which includes most consumer-sized batteries for things like cell phones, cameras and other electronic devices. Airlines say spare batteries must be protected against short-circuiting.

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The battery in Friday’s incident was apparently camera battery, but in 2015 airlines banned "hoverboards" over the risk of fires caused by batteries.

In 2016 the the United Nations' International Civil Aviation Organization temporarily banned cargo shipments of rechargeable lithium ion batteries over the risk of a bad battery causing a phenomenon known as "thermal runaway." The decision, which is in effect until 2018, is not binding but the United States and most other countries comply with its standards.