United Airlines passengers were stranded at airports around the United States for hours on Tuesday due to network outages that affected its airport and website operations.
Hundreds of passengers took to Twitter to complain about lengthy delays to their flights in Buffalo, Des Moines, Phoenix, Houston, Newark, San Francisco and elsewhere.
The company said a "temporary network outage" began about 3pm Eastern time (7pm GMT) and "caused delays and cancellations."
At around 6pm, the company's website was back online and United said in a statement that the outage was resolved and that it was "in the process of resuming normal operations."
"United apologizes for the disruption caused to travelers at affected airports and is reaccommodating customers as quickly as possible. Customers may check their flight status at united.com," it said.
The airline said customers would be able to cancel or rebook their flights without any penalty.
Customers blasted the airline, the country's largest, on Twitter, with some saying they had waited three hours for their flights.
Ted Kobus, delayed at George Bush Intercontinental Airport in Houston, tweeted that United employees were giving refreshments, Oreo cookies and M&M's "to cool the temps of angry customers."