Flight 0429 landed safely on Thursday night in Rapid City, South Dakota, where the injured were taken to the hospital, the U.S. budget carrier said in a statement on Friday.
"Flight attendant was in galley during incident," passenger Derek Lindahl tweeted. "Hit her head on ceiling and completely dislodged the panel. Cuts, neck injury, and concussion."
The airline said it had sent a team to assist the injured and a replacement flight had been sent to Rapid City to fly passengers to Sacramento.
In May, eight passengers were injured when a JetBlue flight from San Juan, Puerto Rico to Orlando experienced turbulence.