An anti-Trump "antifa" protester sucker-punched a black man from behind following President Donald Trump's Tuesday night speech in Phoenix.

The New York Times‘ Simon Romero was on the scene during the post-speech clashes between those who support and oppose the president. He posted a video on Twitter of one such confrontation.

Ugly scene in downtown Phoenix. Watch til the end pic.twitter.com/K516TbufIw — Simon Romero (@viaSimonRomero) August 23, 2017

In the video, a Trump supporter scuffles with a protester before a friend guides him back to his truck. The friend, who is African American, can be heard saying "it's not worth it" and gets in the back of the pick-up truck.

As the truck pulls away from the intersection, a protester enters the frame and punches the friend in the back of the head. The truck pulls into reverse before it drives away.

NBC's Vaughn Hillyard likewise reported there were "punches thrown at Trump supporters in [a] pickup truck that wouldn't drive away."

In the video of the assault captured by Hillyard, the sign held by the assailant can be more clearly seen. It reads "I [love] my Muslim neighbor."