WASHINGTON (CN) — Blasting District of Columbia police for abuse, including rectal probing, four people swept up in mass arrests during Inauguration Day protests sued the District and its Metropolitan Police force Wednesday on civil rights charges.

After several acts of vandalism in downtown Washington on Jan. 20 police used pepper spray, tear gas and flash-bang grenades to push hundreds of people into a confined area, or “kettle,” where they arrested them.

The four plaintiffs — photojournalist Shay Horse, legal observer Judah Ariel, and demonstrators Elizabeth Lagesse and Milo Gonzalez — say police assaulted and battered them and subjected them to unconstitutional abuse, including excessive force and bodily invasions.

Horse and Gonzalez say an officer subjected them to rectal searches after taking them from the kettle to an MPD facility.

“Defendant Officer John Doe 150, who was wearing rubber gloves, ordered Mr. Horse, Mr. Gonzalez, and three other detainees to remove their pants,” the 41-page complaint states. “Without warning, Defendant Officer John Doe 150 grabbed Mr. Horse’s testicles and yanked on them. He then put his finger into Mr. Horse’s rectum, through his underwear.

“As Defendant Officer John Doe 150 pushed his finger into Mr. Horse’s rectum, he ordered Mr. Horse not to flinch. Defendant Officer John Doe 150 pushed his finger an inch deep into Mr. Horse’s rectum and wiggled it around for several seconds.”

The officer repeated this process on plaintiff Gonzalez and three other arrestees, laughed at them with other officers present, and subjected the arrestees to diseases, according to the complaint.

“Defendant Officer John Doe 150 did not change gloves when he moved from one individual to the next,” it states.

Scott Michelman, a staff attorney at the American Civil Liberties Union in Washington, said the ordeal was frightening, disorienting and painful for his clients.

“They’re all shaken to various degrees,” he said in an interview.

“Shay and Milo in particular are dealing with the effects of the rectal searches, which were deeply traumatizing. And all of them really have had scars from that day because of the way in which they were attacked by the police.”

Michelman called of rectal probing and the way it was done “deeply disturbing.”

“As disturbing as the experience that our clients had is the possibility that it was going on that day in a widespread way,” he said.

The use of rectal probing is of particular concern to the ACLU. “Apparently, it goes on here and we’re very concerned about that. Hopefully this lawsuit will help us get to the bottom of that,” Michelman said.

“Whether that was something that MPD is doing more widely, or a targeted punishment that MPD decided to mete out on that day to teach the demonstrators a lesson, it’s deeply disturbing.”

Defendants in the June 21 federal lawsuit include the District of Columbia, Metropolitan Police Department Chief Peter Newsham, 150 Doe police officers and 20 Soe supervisory officers.

The U.S. Attorney’s Office charged 234 people in the Inauguration Day protests. Twelve have pleaded guilty so far; 20 cases have been dismissed.

The MPD said allegations of misconduct will be investigated.

“Each year, the men and women of MPD protect the rights and ensure the safety of thousands of First Amendment assemblies, demonstrations and protests. During the 58th Presidential Inauguration, there were thousands of individuals who exercised their constitutional right to peacefully assemble and speak out for their cause,” the department said in an email.

“Unfortunately, there was another group of individuals who chose to engage in criminal acts, destroying property and hurling projectiles, injuring at least six officers. These individuals were ultimately arrested for their criminal actions, and the bulk of them are pending prosecution after being indicted by a grand jury. As with any pending criminal or civil matter, we will continue to support and respect the formal legal process. Moreover, all instances of use of force by officers and allegations of misconduct will be fully investigated.”

The four plaintiffs say they had nothing to do with vandalism or attacks on police, who bombarded them with pepper spray and tear gas in the kettle without warning.

“The pepper spray and tear gas were so thick that at times they created a haze over the kettle and all the individuals detained there,” the complaint states.

The four plaintiffs say the arresting officers unreasonably denied them access to a toilet, food and water for 7 to 16 hours.

“One of the MPD officers, Defendant Officer John Doe 96, made clear to the detainees that no toilets would be made available by stating in response to one detainee’s request that she should ‘shit [her] pants’ to prove she needed a toilet,” the lawsuit states.

Some arrestees urinated in the streets or in empty bottles. One defecated in a paper bag, according to the complaint.

Michelman said his clients had difficulty breathing under the circumstances.

“There was a lot of panic because everyone was in a confined space and being assaulted with chemical irritants,” the attorney said.

“It’s affected in some cases sleep and personal relationships, willingness to protest further,” he added.

“More broadly, we’re concerned that the tactics and abuses of MPD on Inauguration Day will chill future demonstrators, who may think twice about coming to the nation’s capital to exercise their First Amendment right if they think the result is that they’ll be assaulted by police and kettled and subjected to horrible treatment.”

The District of Columbia did not respond to an emailed request for comment.

The plaintiffs seek damages for violations of the First, Fourth and Fifth Amendments, false arrest, negligence and assault and battery.