(CNN) On an August morning at Wright-Patterson Air Force Base, the medical treatment facility was holding a mass casualty drill. Personnel acting as the injured streamed in.

Across the base, unbeknownst to the medical staff, a second active shooter drill was taking place, with a second set of people pretending to be injured.

Then a real injured person came on the scene: someone who worked at the medical facility hurt their ankle jogging on base, and called another employee screaming and crying.

There was an "incredible convergence of stimuli," Col. Thomas Sherman, commander of the 88th Air Base Wing, told reporters Wednesday. "Sounds, yells, sights. All of those things that are really testing the senses."

In the confusion, someone in the emergency room called the Base Defense Operations Center reporting a real active shooter. Events spiraled from there.

"A breakdown of communication led to a completely uncoordinated and ineffective combined response that could have resulted in serious injury or property damage," the Air Force said in a report summarizing the findings of its investigation into the incident.

How it began

On August 2, the 88th Air Base Wing Inspector General held an exercise at the Kittyhawk Chapel on base. Role-players acted as victims who had been shot. Drills are held twice a year, per Air Force policy.

At the same time, the medical group was holding its hospital drill and mock-patients were coming into the emergency room.

The after-action report says that while the medical drill was "socialized" to the inspector general, it was not noted on the script for the events of the exercise.

How it escalated

After the injured jogger called a coworker at the hospital, they were picked up and brought to the ER, where employees pretending to be injured were also arriving as part of the mass casualty drill.

At the same time, emergency responders on base were hurrying to the chapel as part of the second drill.

A lot was going on at once, Sherman told reporters. "What we had on August 2 on this base was a highly difficult, high-risk scenario," he said.

In the confusion, someone in the emergency room called the base's defense operations center reporting a real active shooter, the report said. The hospital broadcasted a "Code Silver" alert over its intercom system alerting hospital staff to an active shooter situation, and the hospital went into lockdown.

When one employee heard the "Code Silver" alert, they called 911 on their cell phone -- and civilian law enforcement rushed to respond -- what's known as a Code 99 response.

How real shots got fired

Units from the Dayton area and the state of Ohio responded en masse.

At the same time, authorities on base requested a SWAT team. They didn't know about the Code 99 response.

Soon there were officers all over the hospital grounds. "We had a sincere effort from the local community to come provide support. ... They rapidly responded to an event that was unfolding that they believed to be true," Sherman said.

Some of them had problems communicating with the incident commander -- Sherman said that would be the base fire chief on duty -- because the Air Force and local police systems didn't work together. Some never checked in with the incident commander, the Air Force said. Some who did had trouble identifying the chief on the radio.

Air Force security went into the hospital. And when one airman encountered a locked door, five shots were fired.

Other people in the hospital heard those shots, and more calls went out to 911.

Though the incident commander quickly learned that Air Force security had fired the shots, 50 other civilian responders didn't get the message, the report said, "breached the front door of the hospital and entered with weapons drawn."

Officials later deemed the airman's use of a weapon was inappropriate, and left discipline to their commanding officer. The incident is under investigation by the Air Force Office of Special Investigations.

No one was seriously hurt, the colonel said.

What the Air Force is doing in response

The report made recommendations for the base to improve its communications about drill exercises, and inter-operability with state and local first responders.

"We are completely revamping our exercise process," Sherman said at the news conference.

He said he didn't want to second guess the person who called base security because they believed they were truly in danger.

While the base commander wasn't willing to criticize anyone, he repeatedly called the events an opportunity for lessons learned. The goal "is always an effort to make us better," he said.

"I believe that it's not specifically about right and wrong in this case," he told reporters. He said he saw positives in the way authorities from nearby agencies responded to calls for mutual aid.