• Flight-search and booking functions on several major airlines' websites have been restored after being down Monday due to a problem with Google software.
• American, Delta and United apologized to passengers who were unable to search or book flights.
• Google, whose ITA platform provides flights and fares to airline sites, said it has "implemented a fix and the issue has now been mitigated."

Websites of several major airlines were down briefly on Monday due to an issue with Google software that provides price and flight information for these websites.

Websites for American Airlines, Delta Air Lines and United Airlines showed error messages when users looked up flights Monday afternoon but were operating normally after about two hours.

"Earlier today, a data error impacted our flight shopping software, which prevented airline partners, as well as Google Flights, from showing fare information," Google said in a statement. "We've implemented a fix and the issue has now been mitigated. We'll continue to monitor to ensure this is fully resolved."

"Delta.com and the Fly Delta app are functioning normally after experiencing an issue this afternoon that made it difficult for customers to purchase flights on delta.com, the Fly Delta app, and through our Reservations Call Center," Delta said in a statement. "The issue was caused by the failure of technology provided to Delta and multiple airlines by Google. We apologize for any inconvenience this caused."

Also on CNBC

• Beaches top dream vacation wish lists for Americans as travel takes off
• United Airlines tells staff it's hiring hundreds of pilots next month
• American Airlines to use nonunion pilots for some test flights, drawing critics

Subscribe to the CNBC YouTube Channel

Morning Squawk Newsletter