The airline announced the closure in a statement posted to its website on Thursday. It advised passengers to book new flights on other airlines, and said some may be eligible for compensation.
Saurabh Aggarwal, who was due to fly from Toronto to Reykjavik on Wow Air, described a chaotic scene at Toronto airport.
Aggarwal said customers were given conflicting information about the flight's status before it was canceled at 10:55 p.m. She said passengers were not provided with accommodation and no refunds were issued.
"This really scared everyone, at that point we were finally given back our bags and no money as of now has been issued back to me," Aggarwal told CNN.
It wasn't until the following morning that she received an email from Wow Air informing passengers that the airline had ceased operations and all flights were canceled.
Other affected passengers also criticized Wow Air on social media over the lack of communication.
"Just found out about this news," tweeted Jonathan B. Koo, who was stuck at Newark Liberty Airport after his flight was canceled. "They didn't even notify any of us directly, had to find out from twitter and reddit."
A second passenger described "pandemonium at the gate" as he waited for the same flight in Newark. Others tweeted photos of crowds as passengers tried to find out what to do.
Wow Air said in its statement that other airlines may offer reduced fares because of the difficult circumstances.
The budget airline also said that passengers who bought tickets from a European travel agent as part of a packaged tour were protected. Others with travel insurance may also be entitled to claim compensation.
Wow Air said that it may pay compensation "in accordance with European regulation on Air Passenger Rights." If the airline declares bankruptcy, passengers can make a claim with the administrator or liquidator.
Founded in 2011, Wow Air was known for cheap trans-Atlantic fares on routes via Iceland. It's part of a group of Nordic airlines that drove ticket prices down thanks to no-frills service.
It's the latest in a string of airlines to suffer problems as the aviation industry is buffeted by fierce competition and shifting business models.
Primera Air ceased operations in October 2018, leaving travelers stranded on both sides of the Atlantic. In February, German airline Germania filed for bankruptcy and British airline Flybmi stopped flying.