Officials at the Environmental Protection Agency barred reporters from three news organizations, allegedly shoving one out of the building, after they had sought to cover a meeting attended by other journalists Tuesday.

The incident occurred at a summit on water contamination at the EPA’s headquarters in Washington called by the agency’s administrator, Scott Pruitt.

Reporters from CNN, the Associated Press and the energy and environment publication E&E News were prevented from attending the meeting, which included about 200 representatives of regulatory and industry groups.

AP reporter Ellen Knickmeyer tweeted that EPA guards grabbed a reporter by the shoulders and “shoved” the journalist out of the building. Knickmeyer declined to identify herself as the reporter, but AP later confirmed that she was the one excluded.

By midafternoon, the EPA reversed course and permitted Knickmeyer to cover the conference’s afternoon session. Knickmeyer said an adviser to Pruitt called to apologize to her and that officials were looking into the shoving incident, according to AP.

In a statement, Knickmeyer’s boss, AP Executive Editor Sally Buzbee, called the episode “alarming and a direct threat to the public’s right to know about what is happening inside their government.” She added, “It is particularly distressing that any journalist trying to cover an event in the public interest would be forcibly removed.”

CNN reporter Rene Marsh was also prevented from attending, a network spokeswoman said, after “multiple attempts to attend.” The spokeswoman said EPA “selectively excluded” the network and others. “We understand the importance of an open and free press, and we hope the EPA does, too,” she said.

The reserved media list for the event included The Washington Post, the Wall Street Journal, Politico, Bloomberg, the Daily Caller, Hearst, the Hill newspaper, MLive and NJ Advance Media. Several reporters, including those from The Post, did not claim their seats, and instead watched the morning event on a live stream.

EPA spokesman Jahan Wilcox said not all journalists who sought entry could be accommodated. “This was simply an issue of the room reaching capacity, which reporters were aware of prior to the event,” he said in a statement. “We were able to accommodate 10 news outlets and provided a live stream for those we could not accommodate.”

However, reporters and people at the EPA said agency officials have complained about the three news organizations in the past. The agency removed the AP’s environmental reporter, Michael Biesecker, from its master email list last summer after complaining about the fairness of Biesecker’s coverage of Pruitt, who has become embroiled in a series of ethical scandals.

A spokeswoman for E&E News, Kate Ling, said its reporter, Corbin Hiar, was turned away, at first without explanation. She said the agency later said there was no room for him. She said she was not aware of any specific complaints about E&E’s coverage of EPA.

According to Knickmeyer, the agency’s guards prevented the reporter from passing through a security checkpoint inside the building. When she asked to speak to a public affairs representative, the guards grabbed her by the shoulders and forcibly removed her from the building.

Late Tuesday, Wilcox seemed to blame Knickmeyer, saying she was told the event was at capacity on Monday but “proceeded to push through the security entrance” on Tuesday. He said the agency “displaced stakeholders to the overflow room who flew to Washington for this meeting so that every member of the press could have a seat” during the afternoon session.

Although the White House and Trump administration agencies have generally accommodated reporters at public events, journalists protested last year when the White House barred reporters from several news organizations from an informal briefing. CNN, the New York Times, Politico, the Los Angeles Times and BuzzFeed were excluded from the meeting with then-press secretary Sean Spicer, who handpicked representatives from several conservative outlets. Time magazine and AP boycotted the meeting in protest of the exclusion of other news outlets.