John Entwistle,57, the bassist for the rock band The Who, was found dead yesterday in his Las Vegas hotel room, according to MCA Records officials and the Clark County Coroner's Office. The cause of death was a heart attack, Clark County fire spokesman Bob Leinbach said.

Mr. Entwistle's stoical stage presence was a stark contrast to the antics of lead guitarist Pete Townshend and lead singer Roger Daltrey.

Robert Rosenberg, manager of The Who, said he was "saddened and shocked" by Mr. Entwistle's death. The group was to start a U.S. tour today.

The group's concerts were literally explosive -- a fusion of audacious acrobatics, martial precision and high-octane rock 'n' roll that blew away audiences and left the stage and their instruments a smoldering wreck.