Singer Billy Joel struggled to concentrate after the 9/11 terrorist attacks because he sank into a deep depression and constantly felt like he was in a "mental fog". Nearly 3,000 people were killed on 11 September, 2001, after hijackers crashed two planes into the World Trade Center in New York City, sending the Piano Man hitmaker into a deep downward spiral. He was involved in three serious car accidents in just two years following the tragedy, leading many to assume his drink problems were to blame - but the star, who checked into rehab a short time later to conquer his issues, confesses many of his struggles were compounded by depression. Joel tells New York Times Magazine, "I went into a deep depression after 9/11. 9/11 just knocked the wind out of me, and I don't even know if I've recovered from it. It really, really hurt man. And then there was a breakup with somebody, and it took me a while to get me back on my feet again... I was kind of in a mental fog, and it had nothing to do with the booze. My mind wasn't right. I wasn't focused... "The first accident, there was no booze involved. And I didn't hit a tree. It's these really dark roads back up here at night. The car went off the road and into a mud rut. I had been through a breakup and was really broken up about it, and I decided I'm drinking too much. I should go to rehab, but people made a connection, like, 'Oh, he went there because he was in a car accident from drinking.' No. "The second accident was over here on the way out of town. It's called Dead Man's Curve, and it was black ice; that wasn't drinking, either. I went to rehab in '05 because, when I was with Katie (Lee, ex-wife), she said, 'You're drinking way too much.' I never had a D.U.I. in my life. That's another fallacy. Look at the police records."