United Airlines will honor tickets sold for free or close to it for a brief period on Thursday after a human accidentally entered a wrong number.
Passengers reported buying tickets for $5 to $10. United says it accidentally filed fares for $0, although airport charges might have resulted in a small cost.
United stopped taking bookings through its website and phone centers to prevent more of the tickets from being sold or given away. The website was accepting reservations again around 2:45 p.m. Central time.
United spokeswoman Megan McCarthy says the mistake was due to a human error in filing the fares, not a problem with the website. The airline doesn't yet know how many tickets were sold at the unusually low prices.
The Associated Press contributed to this report.