(CNN) A witness to the deadly shooting at an Austin Black Lives Matter protest said the shooter was not defending against violence -- but was initiating it.
The driver accused of shooting Garrett Foster "intentionally and aggressively accelerated their vehicle into a crowd of people" before shots rang out, James Sasinowski said.
"I want to be very clear that the driver incited the violence -- he accelerated into the crowd of people and he shot first," Sasinowski said.
Foster, 28, was marching with other demonstrators during a protest in downtown Austin in solidarity with the Black Lives Matter movement on Saturday evening when he was shot.
Witnesses gave many accounts including that the disturbance began when the vehicle started honking its horn, Austin Police Chief Brian Manley said. Witnesses also told police that Foster approached the car with an AK-47 assault-style rifle while others in the crowd began striking the vehicle.
Sasinowski said he does not know if Foster pointed his gun at the driver and he hasn't heard any of the other witnesses say that happened.
But, he said, the driver initiated the encounter.
"This was intentional. It was aggressive and he accelerated into a crowd of protesters," Sasinowski said. "He could have waited for us to pass or he could have gone slowly. We would have allowed him to go through."
Police responded to a 911 call Saturday in which the caller stated that they had shot someone who had approached their car window and pointed a rifle at them, Manley said.
When officers arrived, they began resuscitation efforts on Foster, but he died shortly after at a local hospital, Manley said.
There will be an autopsy to determine the official cause and manner of Foster's death as the investigation continues, Austin police said.
The driver accused of shooting Foster was brought in by police for questioning, and his handgun and car were secured for evidence, police said. Another person who fired their gun at the car was brought in for questioning. Both had a concealed handgun license and were released pending further investigation.
Austin Police Association President Kenneth Casaday tweeted that Foster was "looking for a confrontation and he found it," a stance he stood by Monday when he spoke to CNN's Chris Cuomo.
"Maybe in hindsight it wasn't the best thing to do, but I stand by what I did. ... I just think that it was the best thing for the community to know at that time," Casaday said.
Casaday said Foster had been protesting in front of the City Manager's house with a rifle.
"You look like you're picking a fight when you're out standing in front of the city manager's house intimidating them," Casaday said.