Boy killed in church by falling bullet

A four-year-old boy has been killed in a US church by a falling bullet fired up to five kilometres away.

The Sun reports the bullet was fired by someone celebrating New Year's Eve before it came down through the church and struck Marquel Peters in the head.

The bullet was discovered in the boy's head by doctors as they worked to save his life.

"I saw his Nintendo game fall on the floor and heard a sound. I heard him scream a little bit," the boy's mother Nathalee, was quoted as saying.

"I looked around and saw blood coming from his head. It's so hard. He was my only child."

The church in Atlanta, Georgia, was holding a midnight service for 150 people.

A ballistics expert with the Georgia State Crime Lab estimated the gun to be a AK-47 assault rifle, fired 3-5 kilometres away at an angle of 30 degrees.

A police spokesman said it was unlikely the person who fired the bullet had any idea of the tragedy that had unfolded.

Experts are reportedly trying to match the bullet to a gun on their database.