A University of Maryland police officer was shot in the head by a member of the Baltimore Police during a training exercise at the former Rosewood Center. (Karl Merton Ferron / February 16, 2013)

The director of Baltimore's police training academy didn't know that instructors were holding exercises at an abandoned psychiatric hospital in Owings Mills. There were no supervisors on site. A police service weapon somehow got mixed up with a practice paint-cartridge pistol. The gun was pointed at a trainee.

Many of the missteps surrounding the exercise at which a University of Maryland police recruit was critically wounded last week ran afoul of nationally recognized training safety standards, according to law enforcement experts and a review of past incidents from around the country.

The incident Tuesday has shaken the city Police Department, leading to suspensions, a criminal investigation and angry soul-searching among commanders and elected officials. If the past is any guide, it is likely to result in dramatic changes to the way city police train.

As law enforcement agencies design training exercises to prepare officers to confront such modern scourges as mass shootings and terrorism, they struggle to balance realism with safety. As the complexity of such operations grows, experts say, the margin of error narrows, increasing the need for rigid safety standards and strict oversight.

State police are still investigating the shooting on the grounds of the Rosewood Center, a former state psychiatric hospital. But Andrew J. Scott III, a national law enforcement consultant, said the details that have become public already show that reform is likely needed.

"This is a horrible tragic accident," said Scott, a former police chief in Boca Raton, Fla. "You can't have enough rigid standards of safety dealing with firearms. Case closed. It's mandatory, it saves lives and it obviously avoids tragedies the likes of what you're seeing in Baltimore."

A pair of accidental deaths in recent years provoked significant changes in the way police and firefighters in Baltimore train. A 2011 shooting of a plainclothes officer outside a nightclub led commanders to order additional preparation for crowd-control operations. The death of a fire recruit in 2007 led the city to end exercises in burning buildings.

While the number of deaths nationwide connected to police training exercises remains small, it has increased in recent years, according to the National Tactical Officers Association, from six in 2009 to 11 in 2010 to 14 in 2011.

Most were from accidental falls, health problems and other causes. The association counted only one death from a gunshot wound in 2011, and only 45 such deaths over the past century.

OpTac International, a law enforcement training firm based in Hagerstown, reviewed more than 20 of those deaths in search of common factors.

OpTac CEO Stuart Meyers found that tight budgets compromise safety by limiting the availability of equipment, supervisors, outside trainers and overtime pay to ensure that the necessary contingent of officers is on hand.

In Baltimore, spending on police education and training fell from $5.7 million in fiscal year 2008 to $3.9 million in 2012. But this year, the department requested $5.3 million.

Police Department spokesman Anthony Guglielmi declined to comment on the training budget or its impact on training practices. He said the accidental shooting is still under investigation.

Meyers, a former SWAT officer who retired from the Montgomery County Police Department after 16 years, interviewed law enforcement officers to develop training safety standards and protocols he distributes to police departments.

The suggestions include notifying dispatch of training locations and prohibiting officers who arrive late or who leave and reappear.

Meyers and others emphasize that the use of service weapons and live bullets is essential to some training exercises.

Officers need to be comfortable training with the weapons they use on the job, they say. Accuracy differs when using real bullets compared with training ammunition. Using a loaded gun places a type of stress on officers for which they need to be prepared.

Meyers said he didn't know whether precautions could eliminate the possibility of friendly-fire accidents during training. "There's always the human element," he said. "I can't tell you with any certainty, but a great deal of them can be prevented."

Last week's shooting comes at a challenging time for new Baltimore Police Commissioner Anthony W. Batts.

Homicides in the city are up nearly 30 percent this year, and Mayor Stephanie Rawlings-Blake has voiced displeasure over the spike — notably after a teen was stabbed to death following the Baltimore Ravens' Super Bowl victory parade this month.