(CNN) -- Three crew members and "a number" of passengers were injured Monday when a United Airlines flight encountered severe turbulence, a spokeswoman for the airline said.
The captain declared an emergency on United Flight 1676, which was flying from Denver, Colorado, to Billings, Montana, said United's Christen Davis. The flight met turbulence as it descended.
"Our primary focus is assisting our employees and passengers who were injured, and our flight safety team will review what happened," the spokeswoman said.
The Federal Aviation Administration said the pilot "declared a medical emergency after a flight attendant was injured by turbulence. The plane landed in Billings without incident."
There were 114 passengers and five crew members onboard, including passenger Bill Dahlin.
"There was a lot of screaming, a lot of hollering," he told CNN affiliate KTVQ.
Dahlin said one woman hit the ceiling so hard that the ceiling cracked. He said he thought the crew was just as surprised by the sudden turbulence as the passengers were.
"I think they were somewhat panicked," KTVQ reported Dahlin said. "I think they were trying to assess things themselves so they really didn't offer any explanation because of what happened so quickly."
Last month, a United Airlines flight returned to Newark Liberty International Airport in New Jersey after turbulence injured five flight attendants.
The plane hit "severe turbulence" about 45 minutes into the Beijing-bound United Flight 89, said Ron Marsico, a spokesman for the Port Authority of New York and New Jersey, which operates the airport.