The plane returned to Dallas-Fort Worth International Airport on Tuesday and landed safely.
Passenger Fred Edwards told WGCL-TV in Atlanta that he heard an explosion before flames came up the side of the plane, lighting up the interior of the Airbus A319. He and other passengers reported that smoke then filled the cabin.
Spirit spokeswoman Misty Pinson said no injuries were reported. She said the captain received an indication of a "possible mechanical issue" shortly after takeoff from the Dallas-Fort Worth airport. She said by email Wednesday that there was no fire, before adding later that Spirit is "actively investigating to confirm the specifics of what happened and the cause."
The passengers were placed on another Spirit jet for Atlanta later Tuesday.
Aircraft engines are designed to contain any broken pieces within the engine during a failure. That's because when parts are released, they often spray like shrapnel and cause severe damage to fuel lines, electrical cables, hydraulic lines and other critical aircraft systems. Airliners are capable of safely flying with only one engine if the other engine breaks down or has to be shut off, but damage from an uncontained engine failure can jeopardize the plane.
Despite the government shutdown, NTSB is recalling furloughed investigators to open an investigation of the incident, the agency official said.
Federal Aviation Administration spokeswoman Laura Brown confirmed the agency is investigating the incident as well.