The death toll was raised after prosecutors said an 8-year-old boy had died, marking the first death of a child in the incident.
Darrell Brooks, 39, appeared in Waukesha County Circuit Court and the court commissioner set bail at $5 million. Authorities said Brooks deliberately drove an SUV through police barricades on Sunday and the annual parade in the city of Waukesha, about 20 miles (32 km) west of Milwaukee.
The high bail comes after Brooks was released from custody in another case after posting $1,000 cash bond on Nov. 11, an amount that the Milwaukee County district attorney's office now says was "inappropriately low in light of the nature of the recent charges" against him.
Brooks on Tuesday was charged with five counts of first-degree intentional homicide, according to prosecutors, who said he has a criminal history in three states. The charges were set before the death of the 8-year-old was disclosed. Prosecutors said more charges were pending.
In addition to those killed, more than 60 people were injured.