Fare frenzy:

An error made some United flights as cheap as $5 for two hours Thursday.

A Hawaiian trip for two for $20? Round-trip flights from Houston to the East or West Coast for even less?

For two hours Thursday, these deals were not too good to be true — sort of.

United Airlines, citing incorrect fare data entered into its computer system, offered $5 to $10 tickets on its website for flights around the country.

The unintended fare sale lasted from 11 a.m. to 1 p.m., before the airline shut down online booking. By then, an unknown number of sharp-eyed fliers, and many more alerted by social media and electronic message boards, had already taken advantage of the superlow rates.

Spokeswoman Mary Clark said afterward that incorrectly

entered information marked ticket prices at $0. That left only fees, which range from $5 to $10. The problem did not stem from a computer glitch, she said.

Clark said fare data are filed into its computer system on a regular basis, and that mistakes can happen when an employee drops a digit or otherwise incorrectly enters. She called them “rare.”

Officials were still trying to determine how many and what flights were affected by Thursday’s goof.

Airline officials shut down online bookings from 1:30 p.m. to 2:30 p.m. and asked customers to call to book reservations by telephone in the meantime.

Clark said Thursday afternoon that the airline was still deciding whether it would honor sales made before the mistake was discovered.

If United does, a lucky number of travelers saved hundreds and perhaps thousands of dollars on trips.

Social media and message boards were buzzing in real time about the opportunity to buy the super cheap tickets.

One Twitter user said she bought two tickets to Maui for $20. Others claimed to be paying as low as $5 per trip to travel to San Francisco, Seattle and New York City from Houston.