Three pilots and 22 members of cabin crew were blue-lighted to hospital suffering from smoke inhalation after the A380 they were travelling in was forced to make an emergency landing.
A further two passengers were seen by paramedics but did not require any hospital treatment.
The British Airways flight was heading from San Francisco to London when its captain declared a medical emergency and made an unexpected landing in Vancouver, Canada.
Immediately, passengers took to social media to express their shock at what had happened. One, Liz Keller, tweeted: “Not reassuring to see firefighters with respirators walking aisles and only be told the crew was taken ill.”
While it is not yet known exactly what happened, Laura Kohli, speaking on behalf of Vancouver Coastal Health hospitals said that all of those rushed to hospital were receiving treatment for smoke inhalation.
A spokesperson for British Airways meanwhile said: “We are sorry for the delay to our customers’ flight but the safety and wellbeing of our customers and crew is always our top priority.
“The flight from San Francisco diverted to Vancouver after members of the cabin crew became unwell.Our ground team at Vancouver has arranged hotel accommodation for the customers and will book them on alternative flights as soon as possible.”
An investigation has now been launched into the cause of why the crew became unwell.
Some reports were suggesting that the crew had been struck down because engine fumes were leaking into the plane, but British Airways said that was not the cause of the issue.
However, despite what could have been a scary situation, passengers are said to have remained calm.
Steve Lowry, 35, who was taking a return flight from a business trip to the US, said passengers were told there was a potential technical fault which had caused crew members to feel unwell.
He said plans were initially made to land in Calgary, but the two-storey aircraft was too big for that airport and had to go to Vancouver.
However, even though passengers were unclear about what was going on, Mr Lowry said: “We were all very British, we were wondering what had happened, and whether they had suffered food poisoning.