GARDINER, Maine — Kennebec County Sheriff Randall Liberty said he is bruised but OK after being shot accidentally by a deputy during a training session at a gun range Thursday.

While at a required firearms qualifying session at a gun range in Gardiner on Thursday, Liberty was shot in the back while a deputy was reloading his pistol. Liberty was wearing his ballistic vest.

“It felt like a hammer hit me right in the back,” Liberty said in a telephone interview Friday. “It was a significant blow.”

Liberty was kneeling with 10 people in a line to his left when he was hit with a .45-caliber round. He immediately told everyone to cease fire.

“It hit just to the right of the center of my spine,” said Liberty, adding that he has a 2-inch-wide bruise in the same spot. “The vest did a good job. It dispersed the blow.”

Liberty said a deputy, whom he declined to name, was reloading his weapon behind a shed about 30 feet behind those shooting on the range. The gun discharged and went through both walls of the shed before hitting Liberty in the back.

Liberty said he has been checked out by a doctor, but is suffering from only bruising and swelling.

“I’m all right,” he said.

An internal investigation is under way. The results are expected by Wednesday, the sheriff said.

Each officer is required to hit 40 out of 50 targets from varying distances and positions in two consecutive sessions as part of Maine Criminal Justice Academy certification, Liberty said. Once the first group is completed, they are supposed to reload their magazines, but keep the gun in the holster and not insert a round into the chamber until the person is ready to shoot on the range.

The way the deputy was reloading his weapon was against department policy, he said.

Liberty said he has worn a ballistic vest for his entire law enforcement career.

“I wear mine every day and have for 30 years,” said Liberty.

Despite having served 24 years in the military and spending time in Fallujah, Iraq, it’s the first time he’s been shot.

“They were never successful [in shooting me in Iraq],” Liberty said.

The incident should serve as a reminder to law enforcement and the public that it is important always to treat a firearm with respect, he said.

“The lesson is no weapon is ever safe. Always point in a safe direction. Complacency kills,” he said. “It’s a lesson for everyone in law enforcement and as we enter hunting season.”

The incident will be reported to the Maine Criminal Justice Academy, which will likely use it as a lesson to students, he said.

Liberty added that it’s the policy of the Kennebec County Sheriff’s Department to require officers to wear ballistic vests on gun ranges, but it’s not a policy for every department.

“In 2012, are you kidding me?” Liberty said, referring to other law enforcement agencies across the country that don’t have such a requirement.