Prosecutors identified the child in court as the suspect in the case, Darrell Brooks, made his first appearance. His hands were shackled and wearing what appeared to be a bulletproof vest.
The 39-year-old Milwaukee man has been charged with five counts of first-degree intentional homicide.
WATCH: Darrell Brooks makes 1st court appearance
Jackson's older brother was also injured in the incident and is recovering in the intensive care unit, WISN reported.
The siblings were marching with their baseball team when they were hit.
The Sparks family has set up a GoFundMe to help pay for expenses during this difficult time.
"I think when things like this happen it's just important to be together in community," said Susan Lewis, a Waukesha resident.
The other victims include four women and a man, ranging in age from 52 to 81.
According to a court complaint, Brooks first brushed a police detective, who "pounded on the driver's side door yelling, 'stop.''
Brooks did not stop but allegedly drove into the parade procession while the detective gave chase. He then allegedly sped up and the detective "heard on the police radio that the vehicle was striking people," the complaint said.
"While the defendant was driving westbound on East Main Street, he struck numerous pedestrians, which included both parade participants and spectators located on the side of the street," the complaint said.
An officer who saw Brooks "observed the driver looking straight ahead, directly at him, and it appeared he had no emotion on his face" as he drove about 25 miles per hour, speeding up and honking his horn as the officer yelled for him to stop.
Brooks' bail has been set at $5 million, which would have to be paid full in cash, and an additional homicide charge is expected. His next court appearance is scheduled for January.
New Video Shows Darrell Brooks After Parade Crash
While this community continues to mourn the loss of six people, there is new video showing the suspect apparently seeking help before police made the arrest.
Doorbell video captured Brooks knocking on a man's front door while on the run from police Sunday.
The video was recorded Sunday by the Ring camera at Daniel Rider's home in downtown Waukesha.
Rider said he was watching football when Brooks rang his doorbell, claiming he was homeless and asked to use Rider's phone to call an Uber.
This, as sirens can be heard closing in.
"I called a Uber, and I'm supposed to be waiting for it over here but I don't know when it's coming. Can you call it for me, please," Brooks is heard on the video as he knocked on Rider's door.
The 24-year-old invited Brooks in, and gave him food and a jacket, then let him use his phone.
Rider said he was still unaware of the deadly parade crash.
"Keep in mind the whole time he had my phone, so my shelter in place and a suspect on the loose messages, I wasn't seeing them," Rider told CNN. "I had no idea anything had happened."
He asked Brooks to leave after he saw police on his street but said the man returned, claiming he left his ID in the house. That's when police showed up and arrested Brooks.
"A minute later, he's pounding on the door saying, 'Let me back in. I left my ID. My ID is in there. Let me back in.' And I'm looking for it as I say, 'no, you stay out there. I'll look for your ID.' And so I'm looking for his ID and it's moments later the police see him and get him in cuffs," Rider said.
Seconds later, cops swarmed the home on Elizabeth Street and arrested Brooks on the front porch.
The Associated Press contributed to this report.