Brian Pomprey, Cornell's agent, said the singer's death was "sudden and unexpected."
Detroit police spokesman Dan Donakowski said: "One of Cornell's friends called the police to the hotel near midnight." When the officers entered the room, they found Chris Cornell lying in the bathroom ... and he was dead. "
Cornell wrote on Twitter earlier: "I finally went back to Rock City."
"The most thing I'm looking forward to," he wrote on Facebook, "is that I do a lot of tours, especially in the last two years alone.