The Federal Aviation Administration, the federal agency charged with overseeing safety in air travel, is now investigating United Flight 1676. The flight, which flew from Denver, Colorado to Billings, Montana encountered severe turbulence last Monday, resulting in five injuries. The plane was flying at 34,000 feet in northern Wyoming at the time of the incident.

The National Transportation Safety Board is gathering information about the cause of the unusual turbulence that sent three flight attendants and two passengers to the hospital after the jet landed in Billings, with one attendant remaining hospitalized.

Christen David, a United spokeswoman, released a statement about the attendant’s status. “We are providing her support, and a United supervisor is by her side at the hospital. Our flight safety investigators are working closely with the NTSB to analyze the flight data.”