"David died peacefully today in his home, and doctors have determined that the cause of death was natural causes."
Insiders in the industry were shocked by Arnold's demise.
The comedy community "mourns the loss of one of the finest to ever do it," said comedian Chris Spencer, a longtime friend of Arnold.
Spencer went on to say that Arnold, a Cleveland native, was "admired by his colleagues, respected by other professionals, and beloved by the emerging comedians he taught."
He would be much missed, particularly by his comedic colleagues."