The cause of death was the oncological disease NEW YORK, February 8. /TASS/. Brad Arnold, the lead singer of the US rock band 3 Doors Down, died at the age of 47. "With heavy hearts we share the news that Brad Arnold, founder, lead singer and songwriter of 3 Doors Down, passed away on Saturday, February 7," the rock band said in the statement posted on its page on the X. The cause of death was the oncological disease.