According to https://www.start.umd.edu/pubs/START_IdeologicalMotivationsO... there have been no deaths from left wing terrorism in the USA for nearly 40 years.
You can read the same information here: https://www.gao.gov/assets/690/683984.pdf
> Specifically, tables 1 and 2 show a description, date, location and number of victim fatalities for each far right [106] and radical Islamist [119] attack between September 12, 2001 and December 31, 2016. During this period, no persons in the United States were killed in attacks carried out by persons believed to be motivated by extremist environmental beliefs, extremist “animal liberation”beliefs, or extremist far left beliefs.