CNN
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Some Delta Air Lines passengers are recovering after experiencing nosebleeds and other discomfort due to a pressure problem on a flight from Salt Lake City, Utah, to Portland, Oregon, according to statements from airlines and passengers.

“We sincerely apologize to our customers for their experience on Flight 1203 on September 15,” a Delta spokesperson said in a statement. “The flight crew followed procedures to return to SLC, where our teams on the ground assisted our customers with their immediate needs,” the airline said.

The passengers of flight 1203 were accommodated on another aircraft.

Delta technicians fixed the pressure problem on the plane, the airline said, and the aircraft was operational again the next day.

Caryn Allen told CNN affiliate KSL that it didn’t take long for passengers to notice that something was wrong on board. “I looked over at my husband and he had both hands over his ears, so he was hunched over a little bit,” Allen said.

“I looked across the aisle about one row behind me and there was a gentleman sitting there who obviously had a very bad nosebleed and people were trying to help him,” Allen told the outlet.

Fellow passenger Jaci Purser said it felt like someone had stabbed her in the ear. “I grabbed my ear and pulled my hand back, and there was blood,” Purser said.

No serious injuries were reported, but medical personnel identified ten people who required evaluation or treatment after the flight.

The Federal Aviation Administration (FAA) announced an investigation.