NORTH MIAMI BEACH, Fla. – A couple killed in what authorities describe as a random attack in Martin County had close ties to South Florida.

Relatives identified the pair as Michelle Stevens, 53, of North Miami Beach, and John Stevens, 59, of southwest Miami-Dade County.

The couple were fatally stabbed in their garage Monday night by Austin Harrouff, a 19-year-old Florida State University student who didn't know his victims, Martin County Sheriff William Snyder said.

Friends and loved ones said Tuesday they were stunned to hear of the killings.

"This was horrendous. I mean, more horrific than anything you could ever think of," friend Wendy Rogovin Green said.

The couple had been married for 19 years. Friends said the pair loved boating and fishing.

John Stevens attended Miami Killian Senior High School. Michelle Stevens, the daughter of popular former North Miami Beach Mayor Jeff Mishcon, was a 1981 graduate of North Miami Beach Senior High School.

"She was a ball of fire," Green said. "Loved life, had a great group of friends. There was never a dull moment in her house. We had so much fun. It's such a tragic loss. It's really heartbreaking."

On social media, friends posted condolences and memories.

"Such a beautiful spirit," Lisa Menckhoff wrote.

Judy Herzfeld wrote that the couple "loved life like no other couple I know."

"You were two of the most amazing people," Ashely Krivoy said.

There was a moment of silence Tuesday night at North Miami Beach City Hall inside commission chambers to honor Mishcon's family.

The former mayor declined to be interviewed, but he wrote a message on Facebook.

"My family and I want to thank you all for your support to help us get through this difficult period," Mishcon said. "We love and appreciate you all."