A photographer for Time magazine was thrown to the ground by a Secret Service agent Monday while covering Donald Trump's rally at Radford University in Virginia.
Another angle showed the photographer clearly being choke-slammed by the agent.
The photographer, Christopher Morris, said the altercation occurred after he stepped outside the press pen.
The Secret Service confirmed that one of its employees was involved in the incident.
Time said it had expressed concerns to the Secret Service about the "level and nature of the agent's response."
In a response on its website, Time said Morris was "briefly detained" following the encounter, where an agent "grabbed Morris' neck with both hands and threw him into a table and onto the ground."
Referring to videos of the encounter, Time said Morris swore at the agent who tried to move him back into the press pen, after which the agent choke-slammed the veteran White House photographer. Time said video also showed that Morris kicked the agent who was trying to restrain him on the ground and also "briefly put his hand on the agent's neck" in an attempt to demonstrate the chokehold he had experienced.
The statement said:
TIME has contacted the U.S. Secret Service to express concerns about the level and nature of the agent's response. Morris has also expressed remorse for his part in escalating the confrontation. A TIME spokesperson said, "We are relieved that Chris is feeling OK, and we expect him to be back at work soon."
The Trump campaign said there was an incident "involving a photographer and a USSS agent" at the rally but directed inquiries to local law enforcement.
A reporter who witnessed the incident also said Morris was "choke-slammed" when he attempted to exit the press pen.
Gabby Morrongiello, a reporter for the Washington Examiner, told BuzzFeed News:
"I believe he was trying to exit the press pen to get a closer shot of a group of students who were protesting Trump. Yes, he was choke-slammed and that's what landed him on the ground.
He was a credentialed member of the media, although Trump's staff is adamant about keeping reporters in the press pen until after the rally has concluded. I believe that is why he was handled like that."