Numbers can be confusing

Today's NY Times has an article entitled "Homegrown Radicals More Deadly Than Jihadis In U.S." The article is based on a report by New America, another Washington Research Center. The article reports that since 2015 "48 have been killed by extremists who are not Muslim, compared with 26 by self-proclaimed jihadists". So, I guess the term 'deadly' can be considered accurate. However, the report does not include the Newtown school or Colorado theater killings. Furthermore, the report states that 276 of the extremists were jihadists, while 183 were not.