A man was sentenced today to more than 25 years in state prison for the fatal shooting of a 5-year-old boy on Halloween six years ago, the Los Angeles County District Attorney's Office announced.

Marcus Denson, 24, pleaded guilty to one count of voluntary manslaughter and two counts of attempted murder in early 2013. He was sentenced today to 25 years and eight months in prison.

Deputy District Attorney Sarika Kim of the Hardcore Gang Division said Leonard Hall, 26, and Denson were members of the Kitchen Crips gang and went into rival gang territory in South Los Angeles on Oct. 31, 2010.

The two men approached the back of a house where a group of men were gathered. Five-year-old Aaron Shannon Jr. was showing his father and others his Spider-Man costume when shots rang out, the prosecutor said.

The boy died from a single gunshot wound to the back of the head and two others were wounded but not seriously injured.

The victims were not associated with any gang.

Hall was sentenced last July to 128 years to life in state prison after a jury found him guilty of one count of second-degree murder and two counts of attempted murder. Gun and gang allegations also were found to be true.

Case BA377814 was investigated by the Los Angeles Police Department.

Los Angeles County District Attorney / Case BA377814 / January 14, 2016