SEATTLE (AP) — Police have arrested a man suspected of stabbing his 11-year-old brother to death in suburban Seattle.

The boy and his 22-year-old brother were involved in a violent confrontation inside a home in Renton on Saturday, KIRO-TV reported. The boy ran out of the home to escape, and officers called to the scene found him lying on a sidewalk.

He was taken to Harborview Medical Center, where he died.

“I got closer and I just saw all this blood,” neighbor Thomas Rountree told the television station. “It literally looked like the kid got into a shower and was just drenched in blood.”

The 22-year-old is being held for investigation of homicide, and police said he appears to have a history of mental illness. Investigators have not released the names of the brothers.