CHATTANOOGA (WRCB)-- A brother is behind bars, after stabbing his sister's boyfriend.

The incident happened Friday morning around 4:00 Boriss Drive.

Police say the sister of 27-year-old William Harrison told them Harrison kicked in her bedroom door and attacked her boyfriend, Martin Macias, stabbing him in the back and cutting his head.

Macias was able to wrestle Harrison down and hold him till police arrived.

When police arrived to the scene, they found drug paraphernalia near Harrison, and he admitted to smoking all night.

He also admitted he was trying to kill Macias, but didn't provide a reason.

Harrison was arrested and charged with aggravated assault and possession of drug paraphernalia.

Macias was treated and released for his injuries.