20 people injured after severe turbulence on Hawaiian Airlines flight to Honolulu

Twenty people, including three crew members, were injured after a Hawaiian Airlines flight en route to Honolulu experienced severe turbulence, in what's being called a "very rare" event, according to officials.

Hawaiian Airlines Flight 35 was flying from Phoenix Sky Harbor International Airport to Daniel K. Inouye International Airport in Honolulu when the pilots reported severe turbulence around 10:30 a.m. Hawaii Standard Time on Sunday, the Federal Aviation Administration said in a statement.

The Airbus A330 was about 30 minutes outside of Honolulu when it began experiencing turbulence, according to Honolulu EMS. The flight landed safely in Honolulu at about 10:50 a.m., according to a statement from Hawaiian Airlines.

Officials said paramedics and emergency medical technicians who responded to the scene treated 36 patients. The flight was full, with 278 passengers and 10 crew members on board at the time, officials said.

Jon Snook, Hawaiian Airlines COO, said during a press conference that 20 people were injured. Of those, 13 people were transported to local hospitals, including three crew members.

Seven of those injured were initially triaged as serious, and nine were triaged as minor, according to Jim Ireland, director of the Honolulu Emergency Services Department. No one is in critical condition at this time, officials said.

They're "grateful that it seems at this moment that none of those guests that were transported to [the] hospital are in critical condition," Snook said.

The youngest patient treated was 14 months old, according to Honolulu EMS.

Injuries included head lacerations, bumps, bruises and loss of consciousness, officials said, and several people experienced nausea and vomiting.

The seatbelt sign was on at the time of turbulence, Snook said. There was unstable air in the area but no warning that the particular patch of air was dangerous, officials said. Specifics on how much altitude was lost were not immediately available.

The flight crew declared an emergency and made a direct descent into the airport where emergency responders were staged, officials said.

This type of event is "very rare," Honolulu EMS Director Jim Ireland said.

"Hawaiian Airlines is continuing to support the 17 passengers and three crew members who sustained injuries today after flight 35 from Phoenix to Honolulu encountered severe turbulence," the airline said in a statement Sunday night. "The Airbus A330 aircraft carrying 278 passengers and 10 crew members landed safely in Honolulu about 10:50 a.m."

"We apologize to our guests for this incident and thank our crew members, first responders, hospital personnel and airport teams for their coordinated response. Hawaiian is conducting a thorough inspection of the aircraft before returning it to service," it added.

"We feel it's fortunate that there were not any deaths or other critical injuries," Ireland said. "And we're also very hopeful that all will recover and make a full recovery, and our thoughts are with all of them and their families. It was a team response today."

The FAA is investigating the incident, the agency said. The National Transportation Safety Board will also be involved in the investigation, officials said.

ABC News' Marilyn Heck and Alex Stone contributed to this report.