The deranged ex-husband of an Indiana tennis star killed his son and daughter in their sleep, and then turned the gun on himself, police said.

Boone County, Indiana cops discovered the bodies of Michael Hunn, 50, and his two children Shelby 13, and Harrison, 15, at the dad’s rural home about 20 miles northwest of Indianapolis just after 10:30 a.m. on Friday, Fox 59 reported.

The children’s worried mom, Stephanie Reece — a former pro tennis player who was a five-time All-American at Indiana University and in 1996 ranked 79th in the world in doubles — called police after the kids didn’t show up for school and didn’t answer the door at Hunn’s house on State Road, the outlet reported.

After Zionsville school officials called Reece around 9:30 a.m., she texted both kids with no response before racing over to the home, the Indy Star reported.

Police forced themselves inside the house and discovered both teens dead in their beds and Hunn lifeless from a self-inflicted gunshot wound.

“I’ll never be able to explain why it happens. It’s a tragic event, we see it all too often and we just don’t have the answers sometimes for why these things occur,” Sheriff Nielsen said. “This is a community that’s come together in the past, it’s going to come together in this particular event as well and we’re gonna try to get through it.”

Investigators are still searching for clues as to why the deranged father would commit such a heinous crime, including using a drone to photograph the property and a 3-D scanner to take copies of the rooms, Fox 59 reported.

Shelby was described as “always such a sweet girl” who was “so funny and crazy and everybody loved her,” a friend told WTHR.

The same friend, who was unnamed, described Harrison, a sophomore in high school and Zionsville tennis player, as “a really great kid.”

“He was there for everybody tried to make people laugh they were having a bad day,” they added.

Another teen said: “Harrison was definitely one of the nicest kids you would ever meet.”

The boy had followed in his mother’s footsteps, playing tennis for his Zionsville high school.

Reece competed at Wimbledon, the U.S. Open, French Open and Australian Open before picking up a job at the East Hampton Indoor Tennis Club on Long Island in 2000, according to an online bio on the Pearson Automotive Tennis Club website.

In 2009, she returned to Indianapolis and currently coaches the girls team at the Zionsville Community High School.

Hunn worked as the general manager of Midwest Studios, a company that creates interactive exhibits, videos and more, according to a University of Indiana newsletter, of which he is an alumnus. He also once worked for American Express in New York City.

Reece and Hunn were married for 17 years before divorcing in November 2017, Indy Star reported. They shared custody of their children and the teens were at their dad’s place during a regularly scheduled visit.

Despite the split, the distraught mom told police relations with her ex were good and she’s in complete shock.

“I spoke to the family and spoke to the mother who is devastated obviously, but she did not see this happening at all,” Boone County Sheriff Mike Nielson said.

However, court documents show ongoing issues between the couple after the settlement was filed.

Reece was concerned about Hunn’s behavior with their children, requesting that his time with them be reduced and his blood alcohol level be monitored, according to a petition filed in December in Boone County Superior Court.

The children had told their grandmother their father wasn’t able to take care of them or drive them to events because of his heavy drinking, the document states.

A mediation agreement filed five months later, shows Hunn agreed to use a breathalyzer and send the results to Reece for 120 days, as well as play weekly child support, Indy Star reported.

But on Aug. 7, Reece filed another petition to hold Hunn in contempt for failure to pay child support, documents show.

The hearing was scheduled for next week.