Former Texas Rep. Beto O'Rouke criticized several protesters who brought rifles to his rally at Kent State University in Ohio.

The Democratic primary candidate held a rally on the university's campus on Wednesday, touting what has become his campaign's signature issue: gun control. Several protesters attended the rally open carrying rifles.

O'Rouke posted a video of his remarks on Twitter.

"It is not enough to stop selling AR-15s and AK-47s when there are more than 10 million of those potential instruments of terror," O'Rourke said. "We must mandate that every one of them be bought back – back home, off the streets, out of our lives – no longer a threat to every single one of us."

"Nobody should show up with one of these weapons to seek to intimidate us in our own democracy," O'Rourke said, pointing at the protesters. "That's wrong. That's wrong."

[Read more: Gun owner tells Beto O'Rourke 'hell no, you're not' taking my guns]

Yesterday, people brought assault weapons to our rally at Kent State—where 4 students were shot dead in 1970.



I told them nobody should show up with an AK-47 or an AR-15 to seek to intimidate us in our own democracy.



We need to buy back every single one of them. pic.twitter.com/U7N5fWUlvv — Beto O'Rourke (@BetoORourke) September 26, 2019

In May 1970, members of the Ohio National Guard opened fire on unarmed students protesting against the bombing of Cambodia, killing four and wounding nine others.

At least some of the protesters were members of the Akron Canton chapter of the Proud Boys.

"We're here to educate and talk," chapter Vice President Andy Walls told Fox 8 Cleveland. "I think the tragedies we've seen from both the Right and Left totalitarianism shows you might need military grade weapons to keep yourself free."

Police arrested one person at the event for reasons law enforcement did not reveal.