The mass shooting at a Walmart in El Paso, Texas, last August that left 22 dead was "the worst carnage wrought by domestic extremists" last year, according to a report released Wednesday that found an increase in the number of white nationalist groups in the United States for the second straight year.
The report by Southern Poverty Law Center reported, which tracks white nationalism, white supremacy and hate groups, identified 155 white nationalist groups in the U.S.