The double-decker bus came flying down the street just as Dr. Manuel Canga lost his way. He says he missed a turn for an embassy and found himself at the wrong place at the wrong time.
Canga, his brother and a close friend were in a white BMW in Union Square on Friday the 13th.
PHOTOS: Several injuries reported after tour bus accident in SF
He told ABC7 News, "I just heard a big bang, like 'Bang!' and I was like, 'Oh my God!' I said, 'What's happening?'"
A City Sightseeing tour bus driver lost control. The driver's attorney says he crashed into some cars in an attempt to stop.
Canga says his brother passed out. He said, "I was screaming for him, I said, you know, 'Wake up, wake up! We have to get out of this car because it's smoking.'"
He says his brother broke his back.
Canga has arm and leg injuries, and says he's traumatized from the event. He said, "I cannot sleep at night. I'm always putting on my brakes every time I drive."
Following the accident, he learned the tour bus wasn't registered with the California Public Utilities Commission and that CHP never inspected it.
"It's very upsetting because it could have been prevented," Canga said.
Canga said he is thankful for the bus driver and realizes, "He did his best to really save a lot of lives."