Justin Bieber's fans must have suffered a heck of a scare tonight.
The 19-year-old star collapsed after experiencing shortness of breath during his show Thursday at London's O2 Arena. He returned to finish the show after receiving oxygen backstage, prompting even more undying loyalty from the Beliebers who packed the venue.
"The fans were so supportive and cheering him on and chanting his name," concert attendee Lauren Odell exclusively tells E! News. "He came back on and finished with 'Believe,' 'Boyfriend' and 'Baby,' but struggled with energy."
Odell 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.
It was Braun who told the audience that a doctor had recommended Bieber cancel the rest of the show, but Bieber insisted on returning, according to concertgoer Tahlia Cave.
Then, Cave says, Braun turned to the young Smith and said, "Jaden, I didn't exactly let you talk. Here you go!" The surprise guest then told the crowd it was time to get pumped for Bieber's return to the stage.
Odell 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," Odell 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."
(Originally published March 7, 2013, at 4:30 p.m. PT)