(CNN) One victim was a security guard trying to keep the peace. The other three victims did nothing to provoke the gunman -- aside from being white , police said.

What the killer didn't know was the stories behind the lives he took. Here's what we know about the victims in the Fresno shooting rampage:

Carl Williams, 25

Carl Williams, an unarmed security guard, was shot outside a Motel 6 on April 13.

Williams was a hard-working security guard who earned the rank of supervisor at Monument Security.

"He was a class act -- there was no other way to put it," his colleague Robert Sanchez told CNN affiliate KFSN

While working at a Motel 6, Williams and the suspect got into an argument, police said. That's when the gunman killed Williams, making him the first victim of the Fresno rampage.

"He lost his life in the line of duty doing security work. It's a tragedy for the security industry," Sanchez said. "He was well-respected within the industry and definitely well-respected within this company."

Zackary Randalls, 34

Zackary Randalls was married with two children. This photo has been digitally altered by CNN to protect the identities of the children.

Randalls was an exceptional father and "loved his two kids with everything that he had," longtime friend Eddie Valencia said.

He worked for Pacific Gas and Electric Co. and was sitting in a company truck when the gunman approached and killed him.

Valencia said he learned of his best friend's death on social media before Randalls' wife found out. So he broke the news to her.

Another friend, Jim Light, said he is most concerned about Randalls' widow and children.

"I don't even know how his wife is going to broach the subject with the kids of daddy's never (coming) home," Light said. "How do you explain that to two small children?"

Valencia vowed to make sure Randalls' children, ages 3 and 4, will grow up knowing who their father was.

He also said Randalls wouldn't want any animosity to stem from his death.

"He wouldn't want this to turn into any type of hateful reaction from anybody in the public," Valencia said . "He would want the focus to be on the love that we got for him, the love that the other families have for their lost loved ones."

Mark Gassett, 37

Mark Gassett was the father of two children, ages 13 and 9.

Every morning, Rosie Wagner looked forward to receiving a loving text from her son.

"Good morning, Mom. I love you," Wagner recalled, dark sunglasses hiding her tears. "(He) called me all the time, making sure I was OK."

Gassett was shot as he was walking away from Catholic Charities with a bag of food, his mother said. But she said she didn't know why, since her son was not homeless.

Gassett leaves behind two sons, ages 9 and 13.

"They're so devastated," Wagner said.

David Martin Jackson, 58

David Jackson tried to flee from the assailant who was targeting white men, police said.

Little is publicly known about Jackson, the gunman's final victim. He tried to flee from the assailant , who eventually caught up with him in the parking lot of the local Catholic Charities.

The police chief said Jackson, like Randalls and Gassett, was apparently gunned down because he was white.