Rittenhouse was taken into custody Wednesday in Illinois. Since Rittenhouse is 17 years old, he is being held at a juvenile Facility in Vernon Hills. Authorities plan to charge him as an adult and extradite him to Wisconsin.
He is now charged with two counts of murder and one count of attempted murder, along with weapons violations.
WATCH: Deadly protest shooting caught on video
The deadly shooting happened during protests and unrest in Kenosha Tuesday night.
Investigators said Rittenhouse was armed with a Smith and Wesson AR-15 style rifle with a 30-round magazine. Open carry is legal in Wisconsin for adults over the age of 18. There was a large presence of armed civilians at the protest.
RELATED: Jacob Blake Shooting: Wisconsin officials name Kenosha officer who shot Blake
Video of the shootings were captured by cell phones. The suspect, now identified by officials as Rittenhouse, can be seen being chased down the street and, at some point, falling to the asphalt. From that position he is seen and heard opening fire with the rifle.
WATCH: Antioch teen charged in Kenosha protest murders
According to authorities, the video shows Rittenhouse casually walking away from the killings, past police.
Rittenhouse was reportedly the only person to shoot anyone during overnight protests.
Video taken earlier Tuesday night, before the shooting, show the alleged gunman explaining why he came from Antioch to Wisconsin.
"We are protecting from the citizens and I just got pepper sprayed by a person in the crowd," Rittenhouse said in the video.
Independent journalist Richie McGinniss interviewed Rittenhouse that night. McGinniss was interviewed by police because he also witnessed one of the shootings.
"People are getting injured. Our job is protect this business. And part of my job is also to help people. If there's someone hurt, I'm running to harm's way," Rittenhouse told McGinniss before the shootings took place.
"I don't know exactly what his motivations were," McGinniss said. "He did tell me that he was there to protect the peace and to provide medical attention."
MCGINNISS: Are you from the area?
RITTENHOUSE: I am from the area.
MCGINNISS: What brought you out here tonight? You just wanted to provide medical attention"?
RITTENHOUSE: Provide medical attention, people are going to need it. Somebody's injured, if you get hurt, I'm grabbing you.
McGinniss is a witness cited in the criminal complaint filed by prosecutors in Kenosha County today.
"The way he was describing what his role was seemed very detached from the way he was being perceived. And so that's what I mean when I say he seemed very naive," McGinniss said.
ABC7 Eyewitness News has confirmed that Rittenhouse is a former member of a youth police cadet program in the northern suburbs. The public safety cadets program included officers from Lindenhurst, Grayslake and Hainseville police departments.
The program gives teens a chance to explore a career in law enforcement.
Rittenhouse was also enrolled as a fire cadet with the Antioch Fire Department, where the chief said they did not have any issues with him during that time.
In the video from before the shooting, Rittenhouse identifies himself as an EMT, shouting, "Medical, EMS right here, I'm an EMT." But the department said he was only enrolled in their explorer program for less than a year.
The chief said Rittenhouse was enrolled as a cadet through a local high school. He was enrolled for less than a year due to COVID-19 cancelling the program.
Neighbors say Rittenhouse was interested in law enforcement, often wearing his cadet uniform around the apartment complex where he lived with his mother. Neighbors say last summer he marched in the July 4 parade as a cadet.
Rittenhouse was a student at Lakes Community High School, but administrators there said he did not graduate. The teen also worked at the YMCA in Volo, where he was on furlough due to COVID-19.
Police said Rittenhouse was with an acquaintance from Antioch the night of the shooting, who was also interviewed by police.
Kenosha police are looking into whether Rittenhouse is linked to local militia groups that wanted to be deputized so they could assist officers in patrolling the streets.
Authorities said some militia leaders have asked to be deputized so they can help stop the violence.
RELATED: Jacob Blake paralyzed from waist down after police shooting in Kenosha, father says
After the gunshots, investigators said Rittenhouse was seen with his hands up walking past several police units.
He went home to Antioch and then turned himself in on a Wisconsin fugitive warrant for first degree intentional homicide, authorities said.
On Thursday, Wisconsin Lt. Governor Mandela Barnes reacted to the charges and why Rittenhouse was even in Kenosha.
"These armed men who have no connection to even the state. The guy is from out of town. So think about how ridiculous that is," Barnes said. "Who is he accountable to? Nobody. And for him to even be able to shoot somebody and walk away from the scene. You know they talk about finding a knife inside the car, not even on Jacob Blake's person. This guy is carrying a long gun, killed somebody just walking freely was able to get back home to Illinois. Then you know we got much bigger problems on our hands."
He is being held without bond and will have an extradition hearing and face murder charges on Friday.