Former White House adviser Dr. Sebastian Gorka on Sunday denounced the alleged gunman who killed 11 people inside a Pittsburgh-area synagogue.

Robert Bowers allegedly entered the Tree of Life synagogue in Squirrel Hill on Saturday and opened fire during a Shabbat service.

Gorka said Sunday on Fox & Friends that Americans need to be on guard to pick up the signs of anti-Semitism.

A report by The New York Times said that Bowers wrote anti-Semitic remarks on a social media platform.

"Unfortunately, evil is real. It walks the Earth and this man was evil," Gorka said.

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Gorka also criticized people who claimed Saturday's events occurred because of a hateful environment created by President Trump.

"The only thing that is evil in this instance is the man who perpetrated this massacre, and the anti-Semitism that he was propagating."

Bowers also reportedly criticized the president in other posts, and in one allegedly called Trump a "globalist, not a nationalist."

"We've got to stop the people who are exploiting tragedy for their own political purposes," Gorka said.

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