A Singapore Airlines flight bound for Singapore returned to San Francisco on Wednesday because of an unruly passenger, The Straits Times, CNA and the San Francisco Chronicle reported.

The airline said a passenger on Flight SQ31 became unruly and injured himself. "The pilots assessed the situation and decided to return to San Francisco," a spokesperson said, as quoted by The Straits Times and the San Francisco Chronicle. The passenger was handed over to local authorities after the plane landed, the airline said.

The flight left San Francisco at 11:51 a.m. local time, which was 2:51 p.m. ET, The Straits Times, CNA and the San Francisco Chronicle reported. It landed back at San Francisco International Airport at about 8:40 p.m. local time, or about 11:40 p.m. ET, nearly nine hours after takeoff.

The flight left again for Singapore at about 11:20 p.m. local time with a new crew, The Straits Times, CNA and the San Francisco Chronicle reported. It arrived at 6:53 a.m. Friday, the Chronicle reported.

Singapore Airlines did not describe what the passenger did or how he was hurt, The Straits Times, CNA and the San Francisco Chronicle reported. The airline apologized to customers and said it was helping them, including by rebooking connecting flights. It said it was working closely with the authorities.

People who said they were on the flight posted online that the man screamed, kicked seats and tried to reach an emergency exit, CNA and the Chronicle reported. Those accounts have not been confirmed by the airline. CNA said one of the posters wrote that the man was arrested.

"We thank our customers and crew members who assisted in managing the situation on board the flight," the spokesperson said, as quoted by The Straits Times and CNA.

What we know: Singapore Airlines Flight SQ31 returned to San Francisco on Wednesday because of an unruly passenger who hurt himself, and he was handed to local authorities.
What we don't: What the passenger did on board and whether he faces charges.