Washington (CNN) President Donald Trump said Friday he does not regard white nationalism as a rising global threat in the aftermath of mosque terror attacks in New Zealand that left at least 49 people dead.

"I don't really," Trump said in the Oval Office after being questioned about whether he views white nationalism as growing. "I think it's a small group of people that have very, very serious problems, I guess."

Three people were arrested in connection with the shootings. They include a 28-year-old man who was charged with murder and was due to appear in court Saturday. The other two remain in custody. New Zealand Police Commissioner Mike Bush said authorities were investigating their ties to shootings that occurred as Muslims convened for Friday prayers, the busiest time for many mosques around the world. The suspected shooter livestreamed video of the attack and posted a manifesto online. In the manifesto, he identifies himself as a white man, born in Australia, and lists the white nationalists who have inspired him.

"If you look at what happened in New Zealand, perhaps that's the case," Trump said on white nationalism. "I don't know enough about it yet. They're just learning about the person and the people involved."

Calling the attack "terrible thing," Trump said he'd not yet seen the manifesto the mosque shooter wrote.

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