All 173 passengers and six crew members onboard an American Airlines flight departing from Denver International Airport had to be evacuated when the plane experienced an issue with its landing gear. Flight AA3023 bound for Miami, Florida was still on the runway when first responders were alerted about the issue on Saturday afternoon and evacuated everybody onboard the Boeing 737 MAX 8, CBS News reports. Video posted online showed passengers frantically exiting the plane on a slide as smoke billowed from underneath the aircraft. Five people were treated at the scene, while a sixth was transported to a local hospital for what has been described as a minor injury. The plane had been scheduled to depart from Denver at 1.12pm, and the FAA said that a 'possible landing gear' incident happened during takeoff on runway 34L. It remains unclear what exactly went wrong during takeoff, but a spokesman for American Airlines said the aircraft experienced a maintenance issue with one of its tires and had to be taken out of service to be inspected. Customers are now said to 're-depart to MIA on a replacement aircraft later today.' The incident has caused more than 200 delays at the Denver Airport as of 7.30 pm EST. The Federal Aviation Administration is now investigating the incident. This is a breaking news story and will be updated.