A University of Maryland police officer was critically injured when accidentally shot in the head during a training exercise on Tuesday. He was transported to Shock Trauma for treatment. (Kenneth K. Lam/Baltimore Sun video)

Top Baltimore police commanders, including the director of the agency's training academy, were unaware that training exercises were being conducted at an Owings Mills facility where a rookie University of Maryland officer was shot in the head and critically wounded, officials said Wednesday.

Anthony Guglielmi, the city Police Department's chief spokesman, called the training at a former state psychiatric hospital a "communication breakdown in the chain of command," and said the department has identified multiple problems — including the fact that there were no supervisors on site.

The revelations came as Baltimore Mayor Stephanie Rawlings-Blake said there was "no acceptable explanation" for the incident.

The state police continued a criminal probe but have characterized the incident as an accident.

The wounded officer, who has not been identified, remained in critical condition Wednesday but was responsive.

Police Commissioner Anthony W. Batts suspended six officers at the police academy, including director Maj. Eric Russell. He has also halted all academy and training exercises pending a safety review. City police can't begin a formal probe until the criminal investigation concludes.

Russell could not be reached for comment.

The officers were taking part in firearms training at the abandoned Rosewood Hospital site, which has been used for training in recent years by the Baltimore County Police Department.

Multiple law-enforcement sources with knowledge of the investigation said they believe the officer who fired the shot mistakenly had his service weapon instead of a "simunition" weapon, which fires rounds similar to paintballs. The circumstances under which the shot was fired, however, remain unclear.

Rawlings-Blake, who met Tuesday evening with members of the wounded officer's family at Maryland Shock Trauma Center, said she had confidence that police would "get to the bottom of it."

"I was so angry I was almost speechless to think that something like this could happen," she said Wednesday. "I made a commitment to the trainee's family that we would get to the bottom of it."

Baltimore City Council President Bernard C. "Jack" Young echoed the mayor's disappointment.

"I'm a little shocked and really displeased that they would use live ammunition in training," he said.

Young spoke Wednesday after a meeting of the Baltimore City Criminal Justice Coordinating Council, where Batts was supposed to introduce his new deputy commissioner, Jerry Rodriguez, a 26-year Los Angeles police veteran who was tapped to run Baltimore's new Bureau of Professional Standards. The bureau oversees internal affairs investigations.

"That bureau is very busy right now," James H. Green, the Police Department's government relations director, told the council, which consists of state and federal law enforcement officials, prosecutors and judges.

Rodriguez's appointment is part of a reorganization as Batts continues to put his stamp on the agency after taking over in September. Training now falls under the direction of Batts' chief of staff, Judy Pal — a civilian whom he hired last fall from a communications job — and Lt. Col. Paul Abell, a veteran who previously oversaw the fiscal section.

While no senior officials were on hand to supervise the training, Guglielmi confirmed that one of Batts' executive protection officers was among the instructors present. Efren Edwards, a 25-year veteran and a training academy instructor detailed part-time to Batts' protection unit, was at Rosewood on Tuesday. He was not the officer who fired the shot; that officer has not been identified.

Batts wrote in a department-wide email that the agency "must do everything we can to learn from this horrible event and be as transparent and forthcoming as possible."

"Our Professional Standards & Accountability Bureau is conducting an over-arching assessment of the incident. They have two goals: determine why this happened, and how we can prevent this type of tragic incident from ever happening again," Batts wrote.

He said the Maryland Police and Correctional Training Commission would also conduct a review. The commission certifies police academies and "prescribes all the training regulations for firearms" in the state, said Mark Vernarelli, spokesman for the Maryland Department of Public Safety and Correctional Services. It also oversees all firearms regulations for all of the police in Maryland, Vernarelli said.