(NewsNation) — A Hawaiian Airlines flight that hit severe turbulence Sunday and left multiple passengers injured could have been “so much worse,” Honolulu’s Emergency Services director said.

The full Hawaiian Airlines flight carrying 278 passengers and 10 crewmembers from Phoenix to Honolulu experienced extreme turbulence at 36,000 feet just before 11 a.m. Airline officials say the aircraft declared an emergency and made a direct approach to the Daniel K. Inouye Airport for landing.

Honolulu Emergency Medical Services and American Medical Response initially responded to reports of 36 people on the flight needing medical attention, ranging from adults to 14 months old, calling it a mass casualty emergency.

Patients suffered cuts, including to the head, as well as bumps and bruises. Some people were nauseous and vomited as a result of extreme motion, he said. Altogether 36 people received treatment.

20 people were rushed to the hospital. Of those, 11 people suffered serious, but not critical injuries and nine had minor injuries. Three Hawaiian Airlines employees were among those hospitalized.

Jon Snook, chief operating officer for Hawaiian Airlines, said it’s the worst case of turbulence he’s seen during his time with the company.

“We’ve been around 93 years, so it’s entirely conceivable there was something worse than that in our history. They are relatively uncommon. We haven’t experienced an incident of this nature in recent history for sure,” Snook said.

Jim Ireland, director of the Honolulu Emergency Services Department, feels fortunate the injuries during the flight were not more severe.

“It could have been so much worse,” Ireland said.

The incident happened as the National Weather Service reported Sunday that a strong cold front impacted Hawaii on Sunday with damaging winds, heavy rain, severe thunderstorms and flooding in parts of the state. Snook insists that the fasten seatbelt sign was on during the bout of bad weather.

“We’re obviously in a situation in the islands right now where we’re dealing with a lot of unstable air and weather conditions that are certainly difficult to deal with if you’re an airline,” Snook said, later adding: “There was no warning of this particular patch of air at that altitude was in any way dangerous. It caught everybody by surprise which is often the case.”

The airline does not have information on how much altitude was lost during the turbulence, but they did report internal damage to the plane with bent and buckled panels that will likely need replacing.

According to Snook, Hawaiian Airlines had three other flight diversions Sunday.

“Maui got hit pretty hard with the weather system and visibility got down to a level which required us to divert three aircraft. So that’s the status at this moment. So nothing to do with turbulence that is related to visibility, low visibility,” Snook explained.

Hawaiian Airlines plans on conducting a follow-up investigation and working with the NTSB as needed.

The Associated Press contributed to this report.