A medical examiner in Michigan says an autopsy has determined that Columbus Blue Jackets goaltender Matiss Kivlenieks died of chest trauma from an errant fireworks mortar blast, and not a fall, as authorities previously reported.

Police in Novi, Michigan, said the mortar-style firework tilted slightly and started to fire toward people nearby Sunday night. The 24-year-old Kivlenieks was in a hot tub and tried to get clear with several other people, police Lt. Jason Meier said.

Meier said that the fire department and EMTs arrived at a private home at 10:13 p.m. local time on Sunday.

Responders took 4 minutes and 38 seconds to arrive after receiving a 911 call. Kivlenieks was taken to a local hospital, where he was pronounced dead.

The Oakland County Medical Examiner's office reported preliminary autopsy results Monday afternoon.

Prior to the autopsy, police said Kivlenieks was believed to have slipped and hit his head on concrete while running from a malfunctioning firework.

"At the moment, we're pretty certain this was a tragic accident," Meier said.

Kivlenieks started in two games for the Blue Jackets this past season and had recently played for Latvia at the IIHF World Championships. He played in eight total games in his NHL career and was expected to compete for more playing time next season.

"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 in a statement. "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."

"One thing I loved and appreciated about him was he had a great smile and always was in a good mood," former Blue Jackets captain Nick Foligno told ESPN's Emily Kaplan in a text message. "I know it's cliché, but that's exactly the kind of guy he was. Just enjoying his life as a 24-year-old living out his dream and you could tell he didn't take one day for granted, which makes this tragedy even more hard to bear. Praying for his family and all of us who knew him. Hard day for a lot of people in that organization."

NHL commissioner Gary Bettman issued a statement on the death of Kivlenieks.

"On behalf of the NHL family, 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 in the statement. "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."

Blue Jackets general manager Jarmo Kekalainen shared his condolences on Twitter.

Life is so precious and can be so fragile. Hug your loved ones today. RIP Matiss, you will be dearly missed.

— Jarmo Kekalainen (@jkekalainen) July 5, 2021

Kivlenieks, who was undrafted, signed with Columbus as a free agent in 2017. He made his NHL debut at Madison Square Garden on Jan. 19, 2020, stopping 31 of 32 shots to beat the New York Rangers 2-1.

Last week, Kivlenieks and fellow Columbus goaltender Elvis Merzlikins made an appearance at the Mid-Ohio Sports Car Course for a ride-along event. Kivlenieks was spending the summer in the United States.

Information from ESPN's Emily Kaplan and The Associated Press was used in this report.