Authorities are investigating how a gunman died after allegedly killing one and injuring three others at a Texas house party on July 26.

Fort Worth Police Department is trying to determine exactly how a man passed away at a backyard party.

Investigators are interviewing witnesses who claim the armed man opened fire on party guests. The group allegedly responded by chasing the gunman and throwing landscaping bricks in his direction. Several projectiles struck the man’s body and fatally injured him. He died shortly after and was declared dead at the scene.

A medical team will conduct an autopsy to establish the cause of death.

BL understands the shooter initially attended the party, became agitated and left. He later returned to argue with other guests before opening fire. He opened fire again when other partygoers pursued him, and continued to fire rounds while he fell to the ground.

Police officers have confiscated a gun they suspect to have been used in the incident. Investigations continue.