Welsh-Ryan Arena transformed from a basketball court into a concert venue Friday night for A&O Blowout featuring rapper Nas and rock band Young the Giant.

A&O chairman Logan Koepke said he was pleased with attendance at the fourth annual show, though an official count was not yet available. Ticket sales increased dramatically among freshmen, with 55 percent of the Class of 2016 buying the $10 passes, A&O spokeswoman Shelly Tan said.

“We were really happy with the freshman ticket sales,” she said. “It’s great to start the year off in that manner.”

The concert kicked off with Young the Giant, who opened with “I Got.” “Cough Syrup,” the band’s hit song, drew screams and cheers from the crowd in the middle of the band’s set. Young the Giant closed with “My Body,” and few in the crowd were not dancing.

Although some students said they were not familiar with Young the Giant before Friday’s performance, Medill sophomore Dana Driskill said she saw the Irvine, Calif.-based band for the first time this summer.

“I would do it all over again,” Driskill said. “I thought they were great.”

During a half-hour break before Nas’ set, NU forward Drew Crawford and other representatives from the basketball program presented Young the Giant with a commemorative basketball.

By the time Nas took the stage, some students had started trickling out of the arena and continued to head for the exits throughout his performance.

“I thought it was really disrespectful that so many students were leaving during Nas,” said McCormick freshman Antonio Jose Vielma, who has tickets to see the New York emcee perform again in several weeks.

Nas’ set featured throwback hits from his early albums (“The World is Yours”) to his more recent work (“Hip Hop is Dead”).

“Despite a lackluster crowd, I was really impressed with Nas’ energy throughout the show,” said Nir Yungster, a McCormick graduate student.

— Cat Zakrzewski