Police are investigating after they say a man stabbed his parents, killing his mother and injuring his father Friday evening in west Houston.

Authorities responded to an aggravated assault call around 5:30 p.m. Friday at a home in the 12300 block of Westella Drive. They say a 20-year-old man stabbed his mother and tried to kill his father, both in their mid-70s.

Police arrived on scene to find the suspect's mother stabbed to death. They say his father was also stabbed and ran to a neighbor's house for help. That neighbor called 911, according to police.

The father was treated at the scene by Houston firefighters and is in ICU at the hospital. Police say the suspect showed no emotion at the scene and was taken into custody without incident.

According to officials, the suspect has a history of domestic violence and drug abuse, and his parents had a protective order against him.