Zachariah Grisham was arrested for accidentally shooting the 3-year-old son of his girlfriend.

An Indiana toddler was killed when his mom’s boyfriend pretended to play shoot him with a gun but forgot it was actually loaded, police said.

Zachariah Grisham, 24, allegedly blasted 3-year-old Lance Wilson in the head during a game at their Michigan City trailer on Sunday afternoon that went tragically wrong.

The live-in lover of the tot’s mom told cops he regularly played a shooting game with the youngster where they would point their fingers and say “bang bang.”

Grisham is accused of grabbing his pistol, pointing the gun at the boy and pulling the trigger.

Zachariah Grisham said he regularly played a shooting game with 3-year-old Lance Wilson at his girlfriend’s home in Michigan City in Indiana, seen above.

He’d forgotten, however, that a bullet was loaded into the chamber.

Police arrived at 3:30 p.m. to find Wilson’s lifeless body sprawled across the floor.

Grisham was arrested and charged with reckless homicide and neglect of a dependent. Appearing in court on Monday, he was held in La Porte County jail on a $100,000 bond.

Neighbors said they comforted the devastated mom as patrol cars and ambulances arrived at her home.

Grisham allegedly forgot there was a bullet in the chamber of the gun on which he pulled the trigger and had pointed at 3-year-old Lance Wilson. The two were playing the shooting game at their home in Indiana.

“She had blood on her hands,” one woman told NWItimes.com. “I felt so bad that this happened. A sweet little innocent boy is gone.”

Neighbor Kim Vansickle told ABC News, “As an adult, you should know better than to play a game with a 3-year-old with a gun. You never know what could happen.”

La Porte County Sheriff’s Department Detective Sergeant Andy Hynek said the tragedy was “an example of why the utmost care must be taken when handling guns.”

“When you pull the trigger at the wrong time, wrong situation, you can’t bring somebody back,” he said.