The Federal Aviation Administration temporarily grounded “certain Boeing 737 MAX 9 aircraft” on Saturday, after a plug door on one of the planes became detached and blew off during an Alaska Airlines flight from Portland, Ore. to Ontario, Calif. The plane was forced to return to Portland and make an emergency landing on Friday evening. No serious injuries were reported, according to Port of Portland’s media team. Alaska Airlines announced the grounding of its Boeing 737-9 aircrafts hours after the incident.