Their flight was headed from Columbus to Phoenix when it made an unexpected landing for a security check at Lambert Airport.
A passenger's son said that they were told that the flight needed to be diverted due to a de-icer issue, but once they landed and police vehicles began to appear, they knew that was not the case.
The passenger's son said officials came on board and escorted one man off of the plane, but later that man was spotted getting on a different plane in St. Louis.
All 113 passengers were evacuated off of the plane while a security check was done.
Bomb sniffing dogs went through the aircraft and all of the luggage was put on the tarmac and also searched by the dogs.
Passengers were bused to Concourse C.
According to a Lambert spokesperson, officials deemed that there was no threat on the aircraft after a couple of hours. However, once passengers did get back on the plane, there were mechanical issues and they were all moved to a different aircraft.
The passengers arrived in Phoenix roughly six hours after their initial arrival time.