Prosecutors in Wisconsin on Tuesday charged a man with intentional homicide over the Christmas parade tragedy.
Darnell Brooks Jr was charged with five counts of first-degree intentional homicide after a car was driven into a crowd in Waukesha on Sunday.
If convicted, he faces a life sentence.
He appeared in Waukesha County Circuit Court and the court commissioner set bail at $5 million.
Prosecutors said six people were killed and more than 60 injured.
A sixth victim — a child — died on Tuesday evening as a result of the parade incident.
Mr Brooks ploughed into the crowds as he was fleeing a domestic disturbance, local police said, ruling out terrorism as a motive.
“We are confident he acted alone,” Waukesha Police Chief Dan Thompson told reporters on Monday.
Mr Brooks had sped away from the scene of a knife fight when police arrived, driving into the parade route, The Washington Post said, citing a local law enforcement official.
Mr Thompson said the suspect was not being pursued by police when the car rammed through the parade.
The deceased include four women and one man, with ages ranging from 52 to 81.
Eighteen children — including three sets of siblings — aged from 3 to 16 were admitted to Children's Wisconsin hospital and 10 were taken to the paediatric intensive care unit, doctors said during a virtual press conference on Monday.
Injuries ranged from facial abrasions to broken bones to serious head injuries.
Two children remain in critical condition, Mr Thompson said.
“While we don’t have all the facts and details yet, we know five families are facing fresh grief of life without a loved one,” US President Joe Biden said from the White House on Monday.
“My administration is monitoring the situation very closely,” he added.
The injured included a dance team of girls aged between 9 and 15, the US state’s Fox6 TV station reported.
Video on social media showed small groups surrounding the injured girls, with white pom-poms scattered on the ground.
On Sunday, Mr Thompson said a sports utility vehicle had been recovered after the incident in the town, about 32 kilometres west of Milwaukee.
A video posted online showed a red SUV ploughing through the parade at speed, appearing to run over more than a dozen people before crowds ran from pavements to offer assistance.
Mr Thompson said an officer fired shots at the vehicle and no bystanders were injured. Police did not believe shots had been fired from the vehicle, he added, contrary to earlier reports. Video on social media appeared to show police firing on the vehicle as it crashed through street barriers.
Belen Santamaria, her husband and their three-year old daughter were planning to join the parade with their church. But Ms Santamaria woke up with a back ache, so the family watched the procession from the pavement instead.
“The SUV came by at full speed,” said Ms Santamaria. “Then I started to hear people screaming.”
She hid in a restaurant with their daughter while her husband, Jesus Ochoa, ran ahead to try to help injured people. He said he heard through other members of their church that about 10 members of the congregation, mostly Latinos and both adults and children, were injured.
“I was going to be there, walking,” Ms Santamaria said. “The SUV would have hit us, too.”
Dance group hit
A woman told Milwaukee's Fox6 TV station that the SUV had hit the dance team and that the immediate reaction was silence, followed by screaming, running and checking on those injured, Fox6 reported.
One witness said the driver also hit a group known as “dancing grannies” and at least one person was flipped over the bonnet of the SUV, Milwaukee's WISN-TV reported.
“Please keep the Grannies, all those injured and all those who witnessed this horrible event in your thoughts and prayers.”
Four members of the dance troupe are among the deceased.
Another witness estimated that the SUV was going about 64 kph when it hit the crowd, the TV station said.