Four people had to be taken to the hospital after a battery fire broke out on a United Airlines flight from San Diego, California, to Newark, New Jersey.
The fire started a few minutes into the flight, forcing the pilot to turn the plane around and return to San Diego. The flight crew managed to put the flaming battery pack into a fireproof bag, preventing it from spreading throughout the cabin.
While preliminary reports indicated the fire was caused by a passenger's laptop, San Diego Fire-Rescue officials told KNSD that the fire was caused by an external battery pack plugged into a cell phone.
While it is unclear what caused the battery to burst into flames, lithium-ion batteries are known to overheat and start fires.
Once the plane landed, the passengers were evacuated from the Boeing 737 MAX 8, and four people, including several crew members, were taken to the hospital with smoke inhalation.
"Our crew acted quickly to contain the device, and medical personnel met the aircraft upon arrival at the gate," United Airlines spokesperson Charles Hobart said. "Several flight attendants were taken to the hospital as a precaution, and two customers were evaluated onsite."
"We thank our crew for their quick actions in prioritizing the safety of everyone on board the aircraft, and we are making arrangements to get our customers to their destinations," he added.
The Federal Aviation Administration is investigating the incident.