A Southwest Airlines plane bound for California returned to Denver International Airport on Thursday after the aircraft’s cabin failed to fully pressurize, according to the airline. Southwest Airlines Flight 4277 turned around after reaching 12,000 feet, when staff aboard the airplane learned of the pressurization problem. No injuries were reported, and oxygen masks were not deployed, the airline said in a statement. The flight departed DIA at 8:39 p.m. and returned by 9:33 p.m., according to the airline and flight-tracking service FlightAware. Passengers aboard the diverted flight to Oakland were accommodated on a subsequent flight. Get more Colorado news by signing up for our Mile High Roundup email newsletter.