One Direction band members meet with Today show host Savannah Guthrie.

One Direction band members meet with Today show host Savannah Guthrie.

An estimated 18,000 One Direction fans are jamming the plaza at Rockefeller Center to watch the lads perform for the second time on NBC’s Today Show Summer Concert Series. It may be one of the largest crowds ever, according to Today weatherman Al Roker.

The lads, Niall Horan, Zayn Malik, Liam Payne, Harry Styles and Louis Tomlinson, are making a much bigger splash compared with their last visit, when they were barely known in the United States.

The band has returned to New York and a far different welcome to promote their biographical film “This is Us,” which premieres in New York City today

Fans began packing into an area about the size of two New York City blocks outside a temporarily renamed Studio 1D, according to the show. Crowd size is based on New York City police department estimates.

“It seems to me this is the biggest crowd we’ve ever had,” Roker said.

The “Today” show is trending worldwide on Twitter, and has been since 7:05 a.m. Eastern, hours before the start of the concert, according to NBC. Tweet your photos and join the conversation with #1DTODAY.

Check out some of the Twitter contributions below and be sure to follow TheImproper for more updates to One Direction’s visit to New York City.

One Direction Fans Mob the Today Show Set; Click Photos to Enlarge

(Photos by Neilson Barnard/Getty Images)