What a trooper!

Justin Bieber experienced breathing troubles during his show at London’s O2 arena tonight and, per eyewitnesses who took to Twitter immediately, the 19-year-old appeared to pass out onstage.

“He got oxygen from emergency personnel. He insisted on finishing the show. He is on the way to the hospital right now,” his rep tells E! News.

Arena sources tell us that Bieber informed the crowd that he wasn’t feeling well and went backstage to get checked out. He returned to the stage about 10 minutes later and finished the show, despite a doctor’s recommendation that he pull the plug.

Video footage from the scene showed Bieber’s manager, Scooter Braun, telling the crowd that the 19-year-old had been feeling “very low of breath” throughout the whole show and was backstage with EMTs.

“The fans were so supportive and cheering him on and chanting his name,” concert attendee Lauren O’Dell exclusively tells E! News. “He came back on and finished with ‘Believe,’ ‘Boyfriend’ and ‘Baby,’ but struggled with energy.”

O’Dell says that Bieber left the stage during “Beauty and the Beat,” the first sign that anything was wrong coming when he lay down on the stairs (“we all thought he was joking around,” she says), and that DJ Tay James was left to improvise after Bieber’s manager, Scooter Braun, came onstage with Jaden Smith to inform the crowd that the teen was struggling to breathe and was being checked out by EMTs.

O’Dell tells E! that, when Bieber returned, he was “really apologetic.”

“He said he was really disappointed and he wanted to give the best performance,” she says. And, even though Braun said that his longtime pal and client wouldn’t be dancing anymore that night, he danced and “was still amazing,” O’Dell says.

“We were really worried,” she adds. “The deejay songs were going out for awhile. We were wondering if something [more serious] happened.”

Bieber was taken to a nearby hospital after the show, according to his rep.

“tough kid,” Braun tweeted later. “proud night. once again he always finishes the show. full out. true pro. now get better and rest up! strange night but proud nt.”

“@justinbieber u got ALOT of love out there,” he wrote. “U stepped up tonight and reading thru these tweets your fans appreciated it. proud to watch.” Braun added: “@justinbieber now get better! love u kid. everyone please give him a little space and he will be ok. Im sure he appreciates the support.”

Source: E!Online/E!Online