CNN) For seven hours, the shooter drove from one target to another, police said, gunning down victims at random.

The gunman shot eight people in three different parts of the county Saturday evening, authorities said.

Around 5:42 p.m., he shot a woman in front of her children at an apartment complex parking lot, prosecutor Jeffrey Getting said. The woman was struck multiple times but is expected to survive.

Four hours later, the gunman killed a father and son at a car dealership, police said.

Minutes afterward, he drove to a Cracker Barrel restaurant and opened fire in the parking lot, killing four women and wounding a 14-year-old girl.

Two of the shootings were captured on video, Getting told CNN on Sunday.

"These were very deliberate killings. This wasn't hurried in any way, shape or form," said Getting, who has reviewed the video with police.

"They were intentional, deliberate and, I don't want to say casually done. Coldly done is what I want to say."

What we don't know:

How the gunman chose the victims.

"There isn't a connection that we've been able to establish between any of the three victim groups with each other, any of the three victim groups with the defendant," Getting told CNN's "New Day" on Monday. "It just is, well, it was random, unprovoked violence."

Kalamazoo County Undersheriff Paul Matyas called it "your worst nightmare" in an interview withCNN affiliate WOOD-TV in Grand Rapids.

The seemingly random selection of victims makes the rampage even more difficult to cope with, said Kalamazoo Public Safety Chief Jeff Hadley.

"There is this sense of loss, anger (and) fear," he said. "On top of that, how do you tell the families of these victims that they were not targeted for any other reason than they were a target?"