22-year-old stabs his younger brother to death with a kitchen knife in broad daylight.

According to Renton police, Bobby Hak, 22, chased his 11-year-old brother Murphy Hak outside their Renton home around noon. He then attacked him on a sidewalk.

Police responded to the scene near Monroe Avenue NE and NE 8th Place in Renton, Washington, where they found the boy lying on the ground.

Medics then rushed the boy to Harborview Medical Center in Seattle, where doctors pronounced Murphy dead.

A witness, Thomas Rountree, said Bobby attacked his brother with a large kitchen knife, and there was "blood all over the sidewalk."

Thomas, who's a next-door neighbor, said:

I got closer, and I just saw all this blood.

It literally looked like the kid got into a shower and was just drenched in blood.

Never in a million years do you think you're going to see a stabbing go down with a young boy.

Police arrested the 22-year-old and booked him for investigation of homicide.

According to the family, the incident unfolded after Bobby began threatening Murphy in their home.

Their mother, Shanty Hak, said Bobby suffers from mental health issues, and he had a virtual visit with his psychiatrist earlier that day.

However, he seemed agitated afterward.

Even though he was on medication for his mental illness, he seemed 'out of control.'

The mom said:

Some medication doesn't work on him.

So, the mom asked her younger son to help her calm Bobby, who was getting increasingly worked up.

At that point, Bobby raced into the kitchen, grabbed a knife and began chasing Murphy.

The mom explained:

That's the time [it] started, and I called Murphy.

I said, 'Murphy, run out of the house.

He panicked because he didn't know what to do.

While the mom tried to intervene, Bobby shoved past her and followed Murphy out onto the street.

Court documents state that Bobby, at one point, said something about 'demons' before racing to his younger brother.

And once the mom was outside, she called out for help from neighbors. But nobody arrived in time.

She said:

By the time I reached him, he had already stabbed Murphy to death.

Footage from the scene showed paramedics tending to someone on the sidewalk while police dragged a shirtless man away.

Murphy's aunt, Thu Carpenter, said the incident has left the family 'absolutely heartbroken.'

Thu said:

This is the side of [Bobby] we did not see coming.