Bob Lee, a technology executive who founded mobile payments company Cash App and previously worked at Square, died Tuesday after being stabbed near downtown San Francisco, according to his family and police.

San Francisco police said officers responded to a report of a stabbing around 2:35 a.m. Tuesday. Officers found Robert Lee, 43, apparently with stab wounds. He was taken to a hospital and died from his injuries, police said.

Police Chief Bill Scott said in a statement Wednesday night that the investigation is in its early stages and called it a horrible crime.

The incident is being investigated by the police department’s homicide department, the department said.

Bob Lee had been working as a product manager for cryptocurrency company MobileCoin. He was previously CTO of Square (now known as Block), a fintech startup co-founded by former Twitter chief Jack Dorsey.

Lee went on to create Cash App, a money transfer service.

“Bobby worked harder than anyone and was the smartest person I’ve ever met. He will be missed by all who knew him,” his father, Richard Lee, said in a Facebook post, which was accompanied by a report on the stabbing. «Thank you to those who have reached out in support.»

The father and son had lived in Miami since October after moving from California, Richard Lee said in the post. They had become especially close after Bob Lee’s mother died in 2019. It was not immediately clear why Lee was back in the Bay Area.

«I’m so sad and heartbroken to lose my brother,» Tim Oliver Lee wrote on Facebook. «He really was the best of us. I was so lucky to grow up with him and I feel like I’ve lost a part of me.»

In a statement Wednesday, Joshua Goldbard, founder and CEO of MobileCoin, said Bob Lee «passed away yesterday» and praised his business acumen. He did not specify Lee’s cause of death.

“Bob was a dynamo, a force of nature. Bob was the genuine article,” Goldbard said. «He was made for the world that is being born at this moment, he was a child of dreams, and everything he imagined, no matter how crazy he was, he made it come true.»

Goldbard said in a twitter thread that Lee was «like a brother to me» and praised Lee as a «brilliant» visionary with a «kaleidoscopic» mind.

The World Health Organization confirmed to NBC News on Wednesday that Lee offered his «support and expertise» during the pandemic, saying in a statement that «Bob built a large portion of the server for the WHO Covid-19 app.»

Lee was also an investor in Elon Musk’s SpaceX company, as well as other tech companies, such as the social audio app Clubhouse, according to his LinkedIn profile. He used the handle «crazybob» for his LinkedIn and Twitter pages.

Scott, the police chief, offered his condolences Wednesday night to Lee’s family and friends.

“There is no place for this type of violent crime against anyone in our city,” Scott said in the statement. «I want to assure everyone that our investigators are working tirelessly to make an arrest and bring justice for Mr. Lee and his loved ones, just as we try to do with every homicide that occurs in our city.»

The fatal stabbing could intensify scrutiny of public safety issues in San Francisco, where residents and business owners are increasingly concerned about violent crime and robbery. Mayor London Breed has vowed to crack down on crime.

San Francisco has had 12 homicides since the start of the year, according to data compiled by the police department. In the same period last year, it had 10 homicides.

Lee’s family, friends and colleagues paid tribute to him.

Krista Lee called her ex-husband «the most amazing and beautiful human being» and said that he «was everyone’s best friend.»

They had two children, Damien, 17, and Scout, 14. Damien Lee said his father was a down-to-earth person who always listened.

“He was such a special person in this world. I am so sad that she has left us so soon,” Damien Lee said in a statement.

Former MMA fighter Jake Shields remembered him as a «loyal friend.» In response to one of Shields’ tweets, Musk said he was «very sorry» to learn of Lee’s death.

Dorsey, the former chief executive of Twitter, called Lee’s death «heartbreaking» on the social media platform Nostr. “Bob was instrumental to Square and Cash App,” Dorsey wrote.

Joshua Bloch, a friend who worked with Lee at Google in the late 2000s, remembers him as a magnetic person who «always had a big smile on his face» and «constantly lived life to the fullest.»

In a phone interview on Wednesday, Bloch recalled that Lee was a technological «self-taught» who could apparently «do whatever he wanted,» adding: «I don’t think he realized how special he was.»

“People always say nice things about the dead,” Bloch said, “but in this case, I would say exactly the same things if I were still alive. He was extraordinary.»