Travelers are reacting to an incident that took place on Alaska Airlines Flight 1282 from Portland, Oregon to Ontario, California last week. The Federal Aviation Administration has grounded Boeing 737 Max 9 Jetliners after part of the plane flying from Portland to Ontario blew out mid-flight. An extensive investigation is being conducted by the National Transportation Safety Board.

Video shot by a passenger on flight 1282, which has been circulating on TikTok, shows an open hole where a wall and window would normally be. Alaska Airlines said in a statement that the incident involved a plug door, a specific panel of the fuselage near the rear of the aircraft. “It was really abrupt. Just got to altitude, and the window/wall just popped off and didn’t notice it until the oxygen masks came off,” passenger Kyle Rinker told CNN.

There were no serious injuries reported after the incident, but several passengers received medical attention. Alaska Airlines said many passengers, “experienced injuries that required medical attention. All guests have now been medically cleared.” The plane was able to land safely back in Portland, allowing passengers and crew to be treated quickly.

Aviation analyst with NBC News and former NTSB investigator, Jeff Guzzetti, speculated on the current investigation. “This is a very new airplane. It was just delivered to Alaska Airlines about two months ago off the factory floor from Boeing with less than 150 flights on it,” he said. “What that tells me is that there potentially could be a manufacturing issue here.”

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Officials appear to agree with him. Eighteen of Alaska’s 737-9 MAX aircraft were pulled from service the day after the event for an inspection and additional maintenance. United Airlines has also suspended service on all flights planned on 737-9 MAX aircraft. Grounded flights have upended the plans of an estimated 25,000 people last Sunday alone, and more cancellations are expected throughout the week. United and Alaska have been working with passengers to change schedules and find accommodations.

“My heart goes out to those who were on this flight. I am so sorry for what you experienced. I am so grateful for the response of our pilots and flight attendants,” said Alaska Airlines CEO Ben Minicucci in a statement. “We have teams on the ground in Portland assisting passengers and are working to support guests who are traveling in the days ahead.”

NBC San Diego interviewed Derik Thoma, who was affected by the change in flight schedules. “It added a whole fiasco of stuff we had to do,” Thoma said. “We had to reschedule our flight. That added a layover, which added an extra night we had to stay. It added a lot to our trip already, and we were looking forward to coming home.”

After hearing about the incident and seeing the video footage, Thoma was more concerned about safety than anything else. “Last night, we were looking up the plane we were flying on today, seeing if there were any issues with this plane,” Thoma said. “It just kind of made us rethink twice about the plane that we were flying on and if [there] are any potential issues with that plane.” This attitude will no doubt be echoed by many airline customers in the coming weeks.