Following the shooting, there was a huge police presence on the scene near the junction Great Hills Trail and Rain Creek Parkway in the Arboretum area of the city.
Interim Austin Police Chief Joseph Chacon said Stephen Broderick was suspected in Sunday's deaths of two women and a man. Chacon said Broderick knew the victims, but didn't elaborate on how or provide a motive for the shootings.
© Austin Police Department via AP Stephen Broderick, 41, in a photo provided by the Austin PD.
The Elgin School District said Monday morning that Simmons and Alyssa Broderick were killed in the shooting.
Officers initially found three adults seriously injured on the scene, all of whom were later pronounced dead.
"This is still an ongoing and active investigation and we do not have this individual in custody yet", Int.
Around 2:30 p.m., the police said the suspect was still at large and asked residents to shelter in place.
"We are concerned that he might possibly take a hostage and be himself sheltering somewhere waiting for us to leave", Chacon said.
First responders are on scene of an "active attack/shooter" incident in northwest Austin, Austin-Travis County EMS (ATCEMS) said Sunday afternoon.
Travis County District Attorney Jose Garza said in a statement that Broderick had been arrested for sexual assault of a child last June and was released on $50,000 bond.
Sheriff's spokeswoman Kristen Dark told the Austin American-Statesman that Broderick, a property crimes detective, resigned after the arrest.
Authorities said they do not know the direction Broderick headed or whether he is in a vehicle or on foot.
A child was also involved in the incident, but was unharmed and is in police custody, authorities said. His wife filed for a protective order and divorce shortly after his arrest.