The man fatally shot by Vallejo police as the city erupted in chaos Tuesday was kneeling outside a Walgreens and not carrying a firearm when an officer opened fire — sending five bullets through his own windshield.

Sean Monterrosa, 22, of San Francisco died after the shooting at around 12:30 a.m. Tuesday, but police did not tell the public the man was killed — or disclose the circumstances of the shooting — until Wednesday at a news conference outside City Hall, a day after calling in 50 troops from the National Guard to help control protests and rioting sparked by the Minnesota police killing of George Floyd.

In a Wednesday afternoon news conference, Vallejo Police Chief Shawny Williams said the officer believed he saw the butt of a handgun poking out near Monterrosa’s waist, and opened fire “due to this perceived threat.”

Williams did not say how far the officer, who was still in his vehicle, was from Monterrosa.

“Investigations later revealed that the weapon was a long, 15-inch hammer, tucked into the pocket of a sweatshirt,” Williams said.

The shooting is under investigation by the Vallejo police and the Solano County district attorney’s office. The officer, an 18-year veteran of the force, has been placed on administrative leave.

The killing early Tuesday morning occurred as protests, lootings and civil unrest erupted across the country. That evening in Vallejo, city officials said about 100 people and nearly 40 vehicles “surrounded” the police department, and rocks and bottles were thrown at officers.

The killing of Monterrosa, who was Latino, is almost certain to fan the flames of an already outraged community, after activists here say for years they have run up against a police department that has disproportionately targeted people of color and is rarely held accountable for its actions.

“My brother was murdered out here by a cop, too — they got no justice,” said Alicia Saddler, who is the sister of Angel Ramos, and who attended the press conference. “Now this man was on his knees? Unarmed? A hammer is not a weapon.”

For Ramos, whose 21-year-old brother was shot and killed by Vallejo police after they responded to a fight at a home, Monterrosa’s death was chillingly familiar.

“He should be here. He should be alive,” she said. “This cop needs to be arrested and taken to jail, period.”

The incidents leading to Monterrosa’s shooting began late Monday evening, when police responded to reports of a looting at a Walgreens on Broadway and Redwood Street, Williams said at the news conference.

Looters initially fled the scene, but about 12:15 a.m. looters had returned and were attempting to break into the building, Williams said. The responding unit reported seeing 10 to 12 potential looters in the parking lot, and police also saw a young man dressed in black, who appeared to be armed, in front of the building, Williams said.

As a police vehicle drove into the parking lot, at least one officer reported potential looters inside two vehicles, a black sedan and a silver truck.

Williams said officers in a second unit saw a single male dressed in black outside the Walgreens, “holding what appeared to be a weapon.”

“This individual appeared to be running toward the black sedan but suddenly stopped, taking a kneeling position, and placing his hands above his waist, revealing what appeared to be the butt of a handgun,” Williams said.

The officer in the second unit opened fire, striking Monterrosa once.

In police scanner traffic of the incident, an officer can be heard saying, “wearing all black, looks like they’re armed—possibly armed.”

“We got shots fired,” an officer is heard saying 22 seconds later.

After the shooting, police scanner traffic captured the ensuing scene, which Williams talked about at the press conference: The black sedan rammed one of the police vehicles, Williams said, which set off the airbag and injured an officer.

The two suspect vehicles fled the scene, prompting a chase into Contra Costa County, where the driver of the silver truck was apprehended, Williams said.

Civil rights attorney John Burris, who is representing Monterrosa’s family, said he was “troubled” by the shooting.

“Notwithstanding what he’s accused of doing, you don’t kill people because they’re looters,” he said.

Burris said he’s awaiting more information on the case, including police body camera footage of the incident.

At the press conference, Williams declined to answer reporters’ and advocates’ questions on whether he believed the officer’s use of force was excessive, but said policy doesn’t preclude police from firing through windshields.

“I would like to say since I’ve been here in the city of Vallejo, we have made many changes in terms of our de-escalation policy, in terms of our body-worn camera policy,” he said. “So there are there are big positive things that are happening.”

When a reporter asked asked how de-escalation was used in this case, Williams said the officers’ intent was to stop and arrest the perpetrators in the Walgreens area.

“The officers reacted to a perceived threat,” he said.

When asked why police waited so long to announce that the shooting was fatal, Williams said he didn’t yet have the information that Monterrosa had died. Williams said on Wednesday he was unaware of the time of Monterrosa’s death, and denied the suggestion that police waited until after the Tuesday evening protest to release the information.

Williams vowed to release body camera footage as soon as possible, prior to the required 45-day legal deadline, in the name of “rapid transparency.”