A SkyWest flight out of Columbia was diverted to Bloomington, Illinois, on Sunday night amid concern about an engine, airline officials said.
Passenger Charlie Fowler said the crew on board United Airlines flight 5228 went immediately into emergency mode.
"We practiced brace positions and the flight attendant, Andy, was yelling 'head down stay down' over and over again," he said.
Fowler said the woman behind him was crying. Another woman called her husband to tell her she loved him.
SkyWest spokeswoman Marissa Snow, said "SkyWest flight 5228, a United Express flight operating from Columbia, Missouri, to Chicago, Illinois, diverted to Bloomington, Illinois, after receiving a mechanical indication. The flight landed safely in Bloomington, and we are working to help passengers resume their travels to Chicago as quickly as possible."
SkyWest said possible mechanical issues caused the pilots to declare an emergency.
City of Columbia spokesman Steve Sapp has directed questions related to the emergency landing to United Airlines.
According to TV station WEEK in east Peoria, the plane touched down at Central Illinois Regional Airport around 7:35 p.m. There were a reported 52 people on board.
Fowler said passengers have been told they'll be taken to Chicago by bus if no other plane is available.