Jordan Fischer for ABC 6 Indiana reports, It may have been a surprise to people who live in Beech Grove, but city officials have known about a military training exercise in the community since March.

Residents were woken up early Tuesday morning by the sound of gunshots at the former St. Francis Hospital.

Beech Grove Police say the U.S. Army Special Operations Command was conducting military training in urban terrain.

At least 100 military personnel were involved in the exercise which started around midnight.

Nearby residents reported loud bangs and explosions and seeing people rappelling from helicopters.

"I went into the bathroom and heard all kinds of commotion and lots of helicopters," Blaine Bonney, a Beech Grove resident, said. "I stuck my head out the window and see one go flying by and another go flying by. They're all circling, making all kinds of patterns."

Bonney said he feels safe, now that he knows what was going on.

"If you hear it's training, and they're out there protecting us and keeping an eye on us, it makes me feel a little safer," he said.

A letter dated March 18, 2016, from the mayor of Beech Grove to the U.S. Army, shows that officials knew well in advance about the training.

The Marion County 911 dispatch center was reportedly "flooded" with calls from concerned Beech Grove citizens — but sources told Call 6 Investigates the 911 call takers were also not alerted to the event, and were caught off-guard.

Beech Grove Police say Marion County dispatch was informed of the training well in advance.