Sen. Jeff Flake (R-AZ) was present at the Republican congressional baseball team practice last week when a gunman opened fire.
House Majority Whip Steve Scalise was among those wounded, and Flake helped apply first aid to his injured colleague after Capitol Police took the gunman down.
The suspect, James Hodgkinson, was a Bernie Sanders supporter and is believed to have been politically motivated.
On "Fox & Friends" this morning, Flake said negative, hateful political rhetoric can lead to violence, and it has to stop.
"We've got to stop, on both sides, on all sides," Flake said. "It's out of control."
He said that political leaders in both parties have a responsibility to speak to their constituents and make it clear that this type of violence is simply unacceptable.
"It does start with us. It will filter down," Flake said. "We just need to model better behavior. We do too much on both sides, and I include myself in that."
Watch more above.