Updated

Washington, D.C. police violated the First Amendment when officers arrested two anti-abortion activists who were writing "Black Preborn Lives Matter" outside of a Planned Parenthood location, one of the activists told "Tucker Carlson Tonight" Monday.

"This is a violation of our First Amendment right," said Warner DePriest, an employee of Students for Life of America (SFLA). "This is viewpoint discrimination."

Video footage shows police warning DePriest and SFLA student leader Erica Caporaletti that they would be arrested if they continued using sidewalk chalk outside of the Planned Parenthood Carol Whitehill Moses Center in northeast D.C.

SFLA said it applied for an event permit that included a request to paint "Black pre-born lives matter" on the street outside of Planned Parenthood. The organization claims that MPD granted them a permit to gather at Planned Parenthood and, in a separate conversation, verbally told them they would not be prevented from painting their message on the street. DC authorities, SFLA claims, specifically requested they use temporary paint.

Alaina Gertz, a public affairs specialist with MPD, told Fox News on Tuesday that police "did not issue a permit to put a message on the street. MPD issues permits to assemble. Any markings on the street would have to be permitted by the DC Department of Transportation."

Later on Tuesday, Gertz said that the permit explicitly stated that "marking or painting on the street is not permitted." She added: "We do not have any information to corroborate the statement that the group was told they would not be stopped from painting."

BLACK PRO-LIFE LEADERS PAN PLANNED PARENTHOOD'S SANGER DISAVOWAL: 'LIKE CHANGING THE NAME OF AUSCHWITZ'

DePriest maintains, however, that when he arrived at the center at 5 a.m. Saturday, police said he couldn't paint "Black Preborn Lives Matter" on the street.

Several U.S. cities, including Washington D.C., have added officially commissioned graffiti and murals to their streetscape in support of the Black Lives Matter movement, with Mayor Muriel Bowser going so far as to rechristen a two-block section of 16th Street NW "Black Lives Matter Plaza."

"The city appears to be covered in political graffiti, racial slurs, obscenities, spray paint --indelible -- on our public buildings," Fox News host Tucker Carlson said. "This was chalk, this was colored dust. Am I missing something?"

"You're not missing anything and that's what's so ironic about this situation," SFLA President Kristan Hawkins replied.

'BABY LIVES MATTER' MURAL PAINTED IN FRONT OF PLANNED PARENTHOOD CLINIC

"I couldn't be more proud of Warner and Erica and the student leaders but more simultaneously afraid [for] our rights because this was clear what was happening was viewpoint discrimination," Hawkins said. "We have a mayor here in Washington, D.C., that painted the streets 'Black Lives Matter,' that allowed activists associated with the Black Lives Matter organization to then go without the permit and [in] permanent paint, paint 'Defund the Police,'" Hawkins added.

SFLA is currently pursuing legal action. As Hawkins noted, activists painted "Defund the Police" in front of the "Black Lives Matter" slogan, so that it reportedly read: "Black Lives Matter = Defund the Police."

According to NPR, the city's Department of Public Works was later seen refreshing some of the paint but left "defund the police" on the street.

"Well it’s not a part of the mural," Bowser told ABC News in June. "And we certainly encourage expression but we are using the city streets for city art." When ABC's Martha Raddatz pressed her further, Bowser said she hadn't "even had an opportunity to review it."

Bowser's office did not immediately respond to Fox News' request for comment.

"We requested permission to paint the streets, 'Black Preborn Lives Matter' because now the mayor has opened up the streets for public expression," Hawkins said. "We didn't hear from the mayor. We were told from the police to use please temporary paint, which we agreed to do. But yet, we saw the mayor's response -- when we arrived on Saturday morning -- with six police cars."

CLICK HERE TO GET THE FOX NEWS APP

MPD told Fox News it remains impartial when following the First Amendment.

"The Metropolitan Police Department respects the right of all individuals or groups to peacefully assemble as their First Amendment right and we remain impartial as to the underlying cause or motive of any group," Hugh Carew, a public information officer, said.