A black man was charged in St. Louis Friday afternoon with setting fire to two predominantly black churches, but authorities are still trying to figure out a motive.

David Lopez Jackson, 35, faces two counts of second-degree arson for the Oct. 18 fire at Ebenezer Lutheran Church and the Oct. 17 fire at New Life Missionary Baptist Church, the St. Louis Post-Dispatch reported.

A total of seven churches in the St. Louis area were targeted in arson attacks last month, six of were predominantly black congregations.

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Police Chief Sam Dotson did not specifically accuse Mr. Jackson of the other church fires but said he was a suspect and suggested that further investigation might result in charges for additional crimes, the Post-Dispatch reported.

Asked about a motive, Chief Dotson said, “We’re still trying to understand that.”

The string of fires, many of which did minimal damage, drew national attention and theories circulated that the fires may have been racially motivated, following the June shooting of nine black congregants at a historic black church in Charleston, South Carolina.

The Rev. Robert Gettinger, of St. Augustine Catholic Church, said news of an arrest was a relief.

“We pray for the person who has done this. It seems to be mentally off-balance behavior,” he told the Post-Dispatch.