Story highlights Trump also called the group a "threat" and accused the group of "essentially calling death to the police"

Trump's comments came as the Republican National Convention got underway

Cleveland (CNN) Donald Trump said Monday he believes the Black Lives Matter movement has in some cases helped instigate the recent killings of police officers, and suggested he might direct his future attorney general to investigate the civil rights activist group.

"Certainly, in certain instances they are," Trump told Fox News host Bill O'Reilly when he asked whether the group has been "a fuse-lighter in the assassinations of these police officers."

"They certainly have ignited people and you see that ... It's a very, very serious situation and we just can't let it happen," Trump said.

Trump also called the group a "threat" and accused the group of "essentially calling death to the police," apparently referring to a 2014 video of protesters in New York City who chanted, "What do we want? Dead cops."

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Those chants came during a protest organized by Millions March NYC demonstrating against police brutality and the group formally disavowed them.

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