Passengers were stuck on a United Airlines plane overnight after a medical emergency forced it to land in Canada

• A United flight from Newark to Hong Kong ended up returning to its departure airport - but not until after spending more than 15 hours at a frozen Canadian airport. 
• Passengers were unable to exit the plane after it landed for a medical emergency because there were no border agents working overnight. 
• The flight was eventually accommodated on a backup plane returning to Newark - and welcoming Canadians sent snacks and Tim Hortons coffee to stranded passengers. 

An unlucky string of events left a United Airlines flight from Newark to Hong Kong stranded on a frozen Canadian tarmac for more than 15 hours as passengers awaited a rescue plane.

United Flight 179 departed Newark Liberty International on time Saturday afternoon, according to flight logs, but landed shortly over five hours later at Goose Bay Airport, a Canadian Forces base in Newfoundland. The airport is a popular refueling spot for private jets headed across the Atlantic and receives multiple emergency landings every month as a result of its location. 

But once on the ground in Canada - where temperatures hit as low as negative 10 degrees over the weekend - the flight crew struggled to re-close an emergency exit door that had been used to evacuate the passenger in need of medical attention. What's more, a lack of overnight border agents meant that passengers were stuck on the Boeing 777 overnight until they could de-plane.

Many of the passengers, including Steven Lau, documented the nightmare on Twitter:

Luckily, some well-wishing Canadians showed up with hot food and warm drinks for the frigid passengers, including - of course - Tim Hortons.

Read more: Canadian air traffic controllers are buying hundreds of pizzas for US colleagues who aren't getting paid in the government shutdown

The backup plane from Newark finally arrived, and passengers were flown back to Newark at 3:30 p.m. the next day, a United Airlines spokesperson said.

"Upon arrival, customers received reimbursement, compensation, hotel accommodations, and meals," the airline said in a statement. "We apologized to our customers for this experience - our crew and operations did everything possible to assist customers during the delay."