The famed ice hockey right winger passed away suddenly Monday morning at his home in Milton, Massachusetts, leaving behind his wife, Kristen Hayes, also 31, and their two young sons.
Their oldest boy, Beau Hayes, had just celebrated his 2nd birthday with a party on Sunday. Their youngest, Mac Hayes, was born this past May.
RadarOnline.com can confirm that the Office of the Chief Medical Examiner in Boston has accepted jurisdiction of the case and that Jimmy's cause and manner of death are pending.
According to The Boston Globe, law enforcement officers and emergency medical technicians responded to the former professional hockey player's home this morning, where he was pronounced dead.
Authorities told the outlet that his death is not considered suspicious; however, the exact cause is not yet known.
Throughout his NHL career – which began in 2011 – he scored a total of 54 goals and 109 points while playing for the Chicago Blackhawks, the Florida Panthers, the Bruins and the New Jersey Devils.
He last played professionally in 2019.
Not even 24 hours ago, Jimmy shared his last Instagram Story – a sweet snapshot from Beau's construction-themed, child-filled birthday party that showed the youngster sitting at a table, waiting patiently for his mom to bring him his beautiful, pickup truck-topped cake.
The late athlete's last Instagram post was dated May 9.
"Happy Mother's Day to this amazing mama!!!" he captioned three photos of Kristen loving up on her two boys. "Can't thank you enough what you do for us we love you so much." He added the hashtag, "#boymom."
As for Kristen, she also documented Beau's adorable event on her Instagram Story, sharing a picture of him in a yellow construction worker's smock, writing, "Pretty much Christmas in august for this 2 year old. You are so loved beau."
She also posted a series of photos showing her carrying her two boys while standing next to her two friends, who were also holding their young sons.
"Let's keep making more babies," she captioned the heartbreaking image. "So much fun celebrating these 3 boys over the weekend. The cutest lil friendships (their dads all played hockey together at BC) if you make it to the end that's a preview of college beau. Can't wait to watch them grow up together."
Fans have since flooded both Jimmy and Kristen's pages with messages of love and support. Vanderpump Rules alum and hockey aficionado Jax Taylor was among them.
"I am so sorry for your loss," the ex-reality star wrote to Kristen. "My wife and I are thinking of you."
The Hayes family also shared a Golden Retriever named Maui.
The couple said "I do" on July 27, 2018.