At least one person has died following an emergency landing of a Southwest Airlines flight in Philadelphia on Tuesday, according to National Transportation Safety Board chairman Robert Sumwalt.

What happened: Per Sumwalt, a Southwest Boeing 737-700 "suffered an apparent engine failure" of the left engine, and they "don’t think there was a fire," contrary to some reports. Sumwalt added the incident will have an "extensive investigation," and that he never "experienced a situation like this" after 10 years of flying a Boeing 737. NTSB is "launching a go-team to Philadelphia" to begin its investigation, per Sumwalt.