Christmas parade deaths heighten tensions in deeply divided US

The deaths of five people mowed down by a car at a US Christmas parade sent another jolt through a country already convulsed by acts of violence and at war with itself over culture, individual rights and the very notion of democracy.

Sunday's incident in the Wisconsin city of Waukesha came two days after the acquittal of Kyle Rittenhouse, a white teen charged with homicide in the same state after fatally shooting two men during racial justice protests last year 50 miles (80 kilometers) away.

Police believe the driver -- a 39-year-old man facing homicide charges -- to have been fleeing a domestic dispute, and have not linked the incident to the trial, or to terrorism.

But in the early hours after the tragedy, right-wing online circles filled with unsubstantiated claims the suspect -- who is Black -- acted in retaliation for the controversial acquittal.

Donald Trump Jr, the outspoken son of the former president, tweeted without evidence that the driver was a "terrorist" left "free to roam the streets while Dems want to throw 17 y/o good samaritans like Kyle Rittenhouse away for life."

It was the latest flare-up in an increasingly incendiary atmosphere that has riven society amid perceptions of rising crime and freefalling trust in government and institutions.

"Our democracy is in trouble," Mary Stuckey, a politics professor at Pennsylvania State University, told , warning against the fixation on drama and conflict in public discourse.