LOS ANGELES, Dec. 13 (Xinhuanet) -- Convicted murder and co-founder of Los Angeles' notorious Crips gang Stanley "Tookie" Williams was executed by lethal injection early Tuesday, hours after California governor Arnold Schwarzenegger refused to save his life.

    Williams, 51, was pronounced dead around 12:30 a.m. at the San Quentin state prison, according to a prison official.

    Williams was sentenced to death in 1981 for killing four peopleduring two armed robberies in Los Angeles two years ago.

    The state and US Supreme Courts and Governor Schwarzenegger turned down multiple appeals for a stay of execution or clemency for Williams over the past two days, clearing the way for his execution.

    Schwarzenegger on Monday said in a statement that he found no justification for granting clemency after studying the evidence, searching the history, listening to the arguments and wrestling with the profound consequences.

    Williams crusaded against gangs and authored several children'sbooks during his last years in death row cell, earning him Nobel Prize nominations for peace and in literature.

    Death penalty opponents and celebrities including civil rights activist Jesse Jackson, rapper Snoop Dogg and Oscar winner Jamie Foxx, who once portrayed Williams in a television movie called "Redemption," had been asking the governor to spare Williams' life.

    No governor has granted clemency since executions resumed in California in 1992, and the last time a governor to grant clemencyto a condemned criminal in the state was Ronald Reagan in 1967.

    Williams formed the Crips street gang in 1971 with a high school friend in Los Angeles and helped build it a nationwide criminal group that continues to spawn street violence more than 30 years later.

    Meanwhile, authorities here reported no signs of unrest in Los Angeles streets in the aftermath of Williams' execution.

    A local police official said the authorities were keeping a close watch on the streets and "everything has been unusually quiet" after the scheduled execution was carried out. Enditem