MORTON COUNTY, N.D. - A law enforcement consultant who trains police dogs is among those condemning the use of guard dogs at a pipeline protest site and says she plans to file a complaint about the dogs’ owner.

Jonni Joyce of Martin, S.D., who has trained professional dogs since 1988, watched video from Saturday’s protest at the Dakota Access Pipeline site and called it “a dark day” for her industry. Some protesters reported being bitten by the dogs, and video from Democracy Now! shows a German shepherd with its mouth covered in blood.

“Taking bite dogs and putting them at the end of a leash to intimidate, threaten and prevent crime is not appropriate,” Joyce said. “It was absolutely appalling. … For a private corporation to utilize dogs in this fashion is reprehensible.”

A Dakota Access spokeswoman declined to comment Tuesday about security personnel or the use of dogs.

The Morton County Sheriff’s Office continues to investigate Saturday’s conflict between a few hundred protesters and private security personnel at a pipeline construction site west of State Highway 1806. Sheriff Kyle Kirchmeier said Tuesday the investigation could lead to charges on both sides.

Frost Kennels of Hartville, Ohio, acknowledged on Facebook the company was involved in Saturday’s incident. Owner Bob Frost did not respond to messages from Forum News Service seeking comment.

On Facebook, the business said “We were simply patrolling an area protecting equipment and we were then ambushed after a fence was torn down and workers and dogs hospitalized.”

Kirchmeier said authorities didn't know about the use of dogs until receiving a 911 call from security.

“It’s a private company protecting their personnel as they see fit," he said.

The sheriff's office is investigating injuries caused by the dogs, Kirchmeier said.

“The injuries that happened against the security people or protesters, have not been brought to our attention at this point," he said.

Three security officers were injured but were not hospitalized, the sheriff's office said.

Joyce said she plans to file a complaint this week with the Ohio Department of Public Safety to determine if Frost Kennels is in compliance with Ohio laws.

“It’s evident by the manner in which they were working the dogs and deploying the dogs that they do not have training,” Joyce said.

Frost Kennels and Bob Frost are not licensed by the state of Ohio to furnish guard dogs or provide security services, said Geoff Dutton, executive director for Private Investigator Security Guard Services through the Ohio Department of Public Safety.

However, Dutton said he doesn’t believe the state’s laws would apply to guard dogs being used in another state.

Keith Rowan, owner of Pro Dog Security in Grand Forks, N.D., said he’d like to see the State of North Dakota Private Investigation and Security Board look into what occurred Saturday.

Rowan, a former K-9 officer for the Grand Forks Police Department, said his security firm has drug detection dogs but never would have used patrol dogs in the manner used at the pipeline site.

“It reminded me of the civil rights movement back in the ’60s,” Rowan said. “I didn’t think it was appropriate. They were overwhelmed and it just wasn’t proper use of the dogs.”

Francine Johnson, executive director for the Private Investigation and Security Board, which licenses private security firms, did not return calls Tuesday.

The American Civil Liberties Union of North Dakota also has criticized the use of dogs, as well as pepper spray, against protesters on Saturday and has urged state officials to “treat everyone fairly and equally.”

“State officials and law enforcement do need to make sure that protesters are not met with excessive force,” said Policy Director Jennifer Cook.

Some protesters have questioned why deputies didn’t intervene when they arrived Saturday. Kirchmeier said Tuesday the agency's goal is making sure everyone is safe, including officers.

"We're not going to put them into a situation to where injuries could happen or if they're not at a point where they have to escalate the use of force, it is not worth it at that point," Kirchmeier said.

It’s unclear if other private security firms were involved Saturday. Donnell Preskey, spokeswoman for the sheriff’s office, said the agency does not have the name of the firm.

The firm 10-Code Security has provided security for Dakota Access in Morton County, according to documents filed in federal court. It’s unknown if the company was involved on Saturday and the firm did not return calls Tuesday.

G4S Secure Solutions issued a statement Tuesday that the company was not involved Saturday. G4S is working with Dakota Access to provide fewer than 10 unarmed security officers to remote sites, but G4S was not present at Saturday’s incident and the firm has not used dogs, a spokeswoman said.

Forum News Service reporter Mike Nowatzki contributed to this story.