Some Delta Air Lines passengers are recovering after a pressurization issue on a flight from Salt Lake City, Utah, to Portland, Oregon, caused bloody noses and other issues, according to airline and passenger statements.

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

Flight 1203 passengers were accommodated on another aircraft.

Delta technicians fixed the pressurization issue on the aircraft, the airline said, and the plane was returned to service the following day.

Caryn Allen told CNN affiliate KSL that said it didn’t take very long for passengers to notice something was wrong on the flight. “I looked over at my husband, and he had both of his hands over his ears, you know, kind of leaning forward,” Allen said.

“I looked about a row behind me, over on the other side of the aisle, and there was a gentleman that clearly had a very bad bloody nose, and people were trying to help him,” Allen told the outlet.

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

No serious injuries were reported, but medical personnel identified 10 individuals in need of evaluation or treatment following the flight.

The Federal Aviation Administration said it will investigate.