KENOSHA, Wis. — A white, 17-year-old police admirer was arrested Wednesday in the killing of two people gunned down during a third night of protests in Kenosha over the police shooting of a Black man, Jacob Blake.

Kyle Rittenhouse, of Antioch, Illinois, was taken into custody in Illinois on suspicion of first-degree intentional homicide. Antioch is about 15 miles from Kenosha.

Two people were shot to death Tuesday night in an attack carried out by a young white man who was caught on cellphone video opening fire in the middle of the street with a semi-automatic rifle.

“I just killed somebody,” the gunman could be heard saying at one point during the rampage that erupted just before midnight.

In the wake of the killings, Wisconsin Gov. Tony Evers authorized 500 members of the National Guard to support local law enforcement around Kenosha, doubling the number of troops sent in. The governor’s office said he is working with other states to bring in additional National Guard troops and law officers. Authorities also announced a 7 p.m. curfew.

“A senseless tragedy like this cannot happen again,” the governor, a Democrat, said in a statement. “I again ask those who choose to exercise their First Amendment rights please do so peacefully and safely, as so many did last night. I also ask the individuals who are not there to exercise those rights to please stay home and let local first responders, law enforcement and members of the Wisconsin National Guard do their jobs.”

One victim was shot in the head and the other in the chest, Sheriff David Beth told the Milwaukee Journal Sentinel. A third person suffered gunshot wounds not believed to be life-threatening.

“We were all chanting ‘Black lives matter’ at the gas station and then we heard, boom, boom, and I told my friend, `‘That’s not fireworks,’” 19-year-old protester Devin Scott told the Chicago Tribune. “And then this guy with this huge gun runs by us in the middle of the street and people are yelling, ‘He shot someone! He shot someone!’ And everyone is trying to fight the guy, chasing him and then he started shooting again.”

Police Apparently Let the Young Man Responsible for the Shootings Walk Past Them

Scott said he cradled a lifeless victim in his arms, and a woman started performing CPR, but “I don’t think he made it.”

According to witness accounts and video footage, police apparently let the young man responsible for the shootings walk past them with a rifle over his shoulder as members of the crowd were yelling for him to be arrested because he had shot people.

Rittenhouse, identified in court papers as a lifeguard at a YMCA in Lindenhurst, Illinois, was assigned a public defender in Illinois for a hearing Friday on handing him over to Wisconsin authorities. The public defender’s office had no comment.

Much of Rittenhouse’s Facebook page is devoted to praising law enforcement, with references to Blue Lives Matter, a movement that supports police. He also can be seen holding an assault rifle.

Other photographs include those of badges of various law enforcement agencies, including the Chicago Police Department. All of the badges have a black line across them — something police officers do with black tape or other material whenever an officer is killed in the line of duty.

In a photograph posted by his mother, he is wearing what appears to be a blue law enforcement uniform as well as the kind of brimmed hat that state troopers wear.

The FBI Said It Is Assisting in the Case

The sheriff told the Journal Sentinel that armed people had been patrolling Kenosha’s streets in recent nights, but he did not know if the gunman was among them.

“They’re a militia,” Beth said. “They’re like a vigilante group.”

The FBI said it is assisting in the case.

Wisconsin Lt. Gov. Mandela Barnes, who is Black, said in an interview with the news program “Democracy Now!” that the shootings were not surprising and that white militias have been ignored for too long.

“How many times across this country do you see armed gunmen, protesting, walking into state Capitols, and everybody just thinks it’s OK?” Barnes said. “People treat that like it’s some kind of normal activity that people are walking around with assault rifles.”

Witness accounts and video show that the shootings took place in two stages: The gunman first shot someone at a car lot, then jogged away, stumbled and fell in the street, and opened fire again as members of the crowd closed in him.

A witness, Julio Rosas, 24, said that when the gunman stumbled, “two people jumped onto him and there was a struggle for control of his rifle. At that point during the struggle, he just began to fire multiple rounds and that dispersed people near him.”

“The rifle was being jerked around in all directions while it was being fired,” Rosas said.

Sam Dirks, 22, from Milwaukee, said he had seen the suspected gunman earlier in the evening, and he was yelling at some of the protesters.

In Wisconsin, It Is Legal for People 18 and Over to Openly Carry a Gun, With No License Required

“He was definitely very agitated. He was pacing around, just pointing his gun in general. Not necessarily at anyone specifically,” Dirks said.

In other widely circulating video, police can be seen tossing bottled water from an armored vehicle to what appear to be armed civilians walking the streets. One of the civilians appears to be the gunman who later shot protesters.

“We appreciate you being here,” an officer is heard saying to the group over a loudspeaker.

In Wisconsin, it is legal for people 18 and over to openly carry a gun, with no license required.

Blake, 29, was shot, apparently in the back, on Sunday as he leaned into his SUV, three of his children seated inside. Kenosha police have said little about what happened other than that they were responding to a domestic dispute. They have not said whether Blake was armed, and they have not disclosed the race of three officers on the scene.

On Tuesday, Ben Crump, the lawyer for Blake’s family, said it would “take a miracle” for Blake to walk again. He called for the officer who opened fire to be arrested and for the others involved to lose their jobs.

The shooting was captured on cellphone video and ignited new protests in the U.S. three months after the death of George Floyd under the knee of a Minneapolis police officer touched off a nationwide reckoning over racial injustice.

During the unrest in Kenosha since then, protesters destroyed dozens of buildings, set fires and hurled objects at police, who responded with tear gas on three straight nights.