The sentencing of an Australian white supremacist who killed 51 Muslim worshippers in New Zealand -- and live-streamed the massacre -- was set to begin amid tight security in a Christchurch court.

The self-avowed white supremacist accused of killing 51 people at two New Zealand Mosques changed his plea from not guilty to guilty. He faces terrorism charges that could land him a lifetime in prison.

Two men were stabbed to death in the U.S. city of Portland on Friday when they tried to stop a man described by local media as a white supremacist, harassing two women who appeared to be Muslim, police said.