Early demand for Marvel’s "Avengers: Endgame" tickets has caused US cinema websites to crash, underscoring predictions that it will deliver the biggest opening weekend of all time later this month.

AMC Entertainment Holdings, the biggest U.S. theatre chain, couldn't handle the traffic when tickets went on sale Tuesday. Fandango, a top ticket supplier, also struggled to meet demand. It put customers in queues, and then told them, "The line is paused."

Disney's Marvel Studios also released a new trailer for the film, helping stoke excitement.

AMC likened the crash to the moment in the previous "Avengers" movie when villain Thanos kills half the people in the universe.

"We want everyone to be able to grab their Avengers: Endgame tickets, but it looks like we've gotten Thanos' snap," the movie chain told customers on Twitter.

The movie has also broken records. Fandago announced that the movie set a new record for first-day tickets sales within just six hours.

Box Office Pro is forecasting opening-weekend sales of $265 million in North America for "Endgame," which opens on April 26. That would exceed the record $257.7 million set by its predecessor "Infinity War" last year.

Box Office Pro also projects $645 million for the film's full domestic run. That's short of the $936.7 million record set by another Disney film, "Star Wars: The Force Awakens," according to Box Office Mojo.