The 25-year-old Sudanese immigrant who shot up a Tennessee church on Sunday left a note in his vehicle referencing white supremacist Dylann Roof’s attack on a black church in Charleston.

The Associated Press reports that Emanuel Kidega Samson left the note in his vehicle before opening fire on members of Burnette Chapel Church of Christ, a small church outside of Nashville.

Samson, an amateur bodybuilder who came to the U.S. in the 1990s, killed one woman in the attack and injured six other people. He was stopped when a 22-year-old member of the church retrieved a gun out of his car. The man, Robert Engle, held Samson until police arrived. (RELATED: 22-Year-Old With Concealed Carry Stops Tennessee Shooter)

The AP did not report any other details of Samson’s letter, portions of which investigators read to the news outlet on the condition of anonymity. In July 2015, Roof entered the Emanuel African Methodist Episcopal church in Charleston and killed nine people. Roof has since been sentenced to death for the killings.

Authorities have still not officially released a motive for Samson’s attack on the church, which has a racially diverse membership.

The FBI and Justice Department have opened a civil rights investigation into the shooting.

In the months prior to the shooting, Samson had had the police called on him during several domestic disputes. His father also called authorities over the summer after Samson threatened to commit suicide.

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