Police in Michigan believe that the mortar was lit properly but shifted and began firing at people, including Kivlenieks, who were in a hot tub. The goalie was hit in the chest while trying to take cover.
Kivlenieks was dead by the time he arrived at a local hospital.
It’s with a very heavy heart that we share the news that goaltender Matiss Kivlenieks passed away last night at the age of 24.
We are heartbroken. Please keep his family in your thoughts and prayers.
"We are shocked and saddened by the loss of Matiss Kivlenieks, and we extend our deepest sympathies to his mother, Astrida, his family and friends during this devastating time," Blue Jackets President of Hockey Operations John Davidson said. "Kivi was an outstanding young man who greeted every day and everyone with a smile and the impact he had during his four years with our organization will not be forgotten."
NHL commissioner Gary Bettman also released a statement on the league's behalf.
"We extend our deepest sympathies to his family, friends and teammates in both the Blue Jackets organization and his native country of Latvia," Bettman said. "His love for life and passion for the game will be deeply missed by all those who have been fortunate to have him as a teammate and a friend."
Kivlenieks signed with the Blue Jackets in May 2017 as a free agent. He went 2-2-2 and recorded a 3.09 goals-against average and .899 save percentage in eight games with the team.