Story highlights Police say the boy opened fire after repeated break-in attempts by the teen

A neighbor questions the account to CNN affiliate KMOV, saying the boys were arguing on the front porch

(CNN) An 11-year-old St. Louis-area boy left alone at home with his 4-year-old sister staved off several home invasion attempts before finally shooting and killing a 16-year-old intruder, according to police.

At least one neighbor, however, offered a different account of the shooting, telling CNN affiliate KMOV that the boys were arguing on the front porch before the younger child pulled out a gun and shot the teenager.

The incident occurred Thursday afternoon in north St. Louis County. Police called to the home discovered the teenager's body lying in the front foyer.

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The teenager -- whose name has not been released -- had been shot in the head by the 11-year-old while breaking into the home, according to police.

St. Louis County police Sgt. Brian Schellman said it was the third time that the 16-year-old had attempted to break into the house Thursday. Neither sibling was hurt.

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