President Trump declared Saturday's mass shooting against the Tree of Life Synagogue in Pittsburgh a "anti-Semitic act."

"This was an anti-Semitic act," Trump said at the Future Farmers of America event in Indianapolis. "You wouldn't think this would be possible in this day and age, but we just don't seem to learn from the past."

Trump called the persecution of Jews "one of the ugliest and darkest features of human history" and said there should not be any room for antisemitism or "any form of religious or racial hatred or prejudice" in the U.S.

[More: Mike Pence, Trump family react to deadly synagogue shooting]

The suspected gunman in custody, Robert Bowers, is accused of killing at least 10 people who had gathered at the synagogue, located in Pittsburgh's Squirrel Hill neighborhood.

Worshipers at the synagogue had reportedly gathered for a baby naming ceremony. Several people were killed and six people were injured, including four police officers who were shot as they worked to rescue the people inside the synagogue. Local law enforcement confirmed that they did not find any evidence of explosives.

The attack is being investigated as a hate crime led by the FBI, and Trump said federal officials would conduct a "full and thorough" investigation. He praised law enforcement officials for the work they were doing.

"We must all rise above the hate, move past our divisions, and embrace our common destiny as Americans," Trump said. "And it doesn't mean that we can't fight hard and be strong and say what's on our mind, but we have to always remember those elements. We have to remember the elements of love and dignity and respect and so many others."