FLINT, Mich. – A pickup truck slammed into a crowd of "Fight for $15" protesters Tuesday during a rally in Flint, injuring nine people, officials said.

Michigan's Democratic gubernatorial candidate, Gretchen Whitmer, was among those participating in the rally, where protesters demanded a higher minimum wage.

Whitmer wasn't injured, but she posted on Twitter that she's "incredibly sad that so many people were hurt."

Police said nine people were hurt, but it's unclear if they were all brought to the hospital or treated at the scene and released.

The incident happened on Dort Highway, where protesters had started to march north during the rally. There were about 200 people involved in the protest.

"Loud noise, screaming, and then right after it, one of the rally people ran up to the front of the truck, banging on the window, yelling, 'What are you doing? Why did you do that?'" a photographer who witnessed the incident said.

He said he heard the pickup truck come down the street screeching its wheels and saw it slide sideways into the group of protesters.

It doesn't appear there was a police car in the back of the protesters, officials said.

The driver of the pickup truck is cooperating with police and has not been arrested, according to authorities.

Whitmer said she was at the front of the line during the protest and didn't know that the crash had happened until SEIU management told her there was an accident and that she should leave for safety reasons.

She said she plans to reach out to the people directly injured in the incident.

Flint Mayor Karen Weaver's office released a statement sending thoughts and prayers to the victims as its follows up on the investigation.