An American Airlines flight from Chicago to Dallas-Fort Worth made an emergency landing in St. Louis due to a medical emergency in the cockpit.
According to the airline, the first officer became ill not long after Flight 2309 left Chicago. A pilot happened to be in the jump seat and took over for the first officer.
After landing, the first officer was met by paramedics and transported to a nearby hospital.
The condition of the first officer is not yet known, but NBCChicago.com is reporting the pilot was suffering from chest pains.
A new crew was assigned in St. Louis and the flight landed at DFW Airport at 1:37 p.m.
The flight had already experienced a one-hour maintenance delay in Chicago before leaving for Dallas.
"It's scary when they come on and say 'we have a problem, we need to divert to St. Louis,' probably the worst part right there is, you don't know what the problem is, so you don't know if it's medical like that," said Dave Barber of Grand Prairie.
American Airlines would not comment on the situation or the pilot. He was taken to a hospital in St. Louis.
NBC 5's Omar Villafranca contributed to this report.