As testimony began, Olympic diver Bruce Kimball unexpectedly switched his plea to guilty in his drunken-driving manslaughter trial, admitting that he sped into a crowd of teen-agers last summer, killing two and injuring four.

In the face of strong evidence, the 1984 Olympic silver medalist pleaded guilty to two counts of driving under the influence manslaughter and three counts of causing great bodily harm while driving under the influence in the late-night Aug. 1 tragedy. He faces up to 22 years in prison.