Here is a list of killings that have happened at USA churches since 2012:
December 29, 2019: A killer murdered two people during the morning service at West Freeway Church of Christ in Fort Worth, Texas, before he was fatally shot by a volunteer member of the church security team.
November 5, 2017: A killer opened fire at the First Baptist Church of Sutherland Springs, Texas, killing 26 people and wounding about 20 others. No church security team was in place to stop it.
[ Read the SemperVerus article, Majority of Protestant Churches Plan for Security ]
September 24, 2017: A man killed a woman and wounded six other people at Burnette Chapel Church of Christ in Nashville, Tennessee.