Bob Lee, the 43-year-old creator of Cash App and former CTO at Jack Dorsey’s Square, now Block, was stabbed to death in San Francisco on Tuesday morning.

Lee’s death was reported by NBC Bay Area and TechCrunch and later confirmed by Dorsey in a post on his social network, nostr. The tech executive’s passing was also confirmed by his boss Joshua Goldbard, the CEO of MobileCoin, a privacy-focused cryptocurrency and payments company. Lee worked at MobileCoin as the chief product officer. No arrests have been made. 

“Bob was a dynamo, a force of nature. Bob was the genuine article. He was made for the world that is being born right now, he was a child of dreams, and whatever he imagined, no matter how crazy, he made real,” Goldbard told Gizmodo in an email. “From large contributions to Android at Google, to being the first CTO of Square, in that time creating CashApp, and working with us here at MobileCoin, Bob surely had an impact that will last far beyond his short time on Earth.”

According to a statement from the San Francisco Police Department, the incident that took Lee’s life occurred at around 2:35 a.m. on the 300 block of Main Street, where they found a 43-year-old adult male victim “suffering from apparent stab wounds,” which were described by police as life-threatening injuries.

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Police stated that despite efforts by first responders and medical personnel, Lee died from his injuries.

Over on nostr, users expressed shock that the news was real.

“It’s real,” Dorsey said. “Getting calls. Heartbreaking. Bob was instrumental to Square and Cash App. STL guy.”

Twitter CEO Elon Musk also weighed in on Lee’s death early on Wednesday. In response to a tweet from Jake Shields, a former world mixed martial arts champion, who expressed outrage that Lee, his friend, was killed in the “good” part of San Francisco.

“He was in the ‘good’ part of the city and appeared to have been targeted in a random mugging/attack. Fuck San Francisco,” Shields tweeted. Police said Lee was stabbed in the Rincon Hill neighborhood near the Bay Bridge to Oakland, a part of the city’s office-heavy financial district.

Musk told Shields he was sorry to hear about Lee’s passing and said he knew many people that had been “severely assaulted.”

“Violent crime in SF is horrific and even if attackers are caught, they are often released immediately,” Musk said, going on to mention San Francisco District Attorney Brooke Jenkins. “Is the city taking stronger action to incarcerate repeat violent offenders @BrookeJenkinsSF?”

According to TechCrunch, Lee joined Block after spending a few years at Google working on Android. At Block, Lee focused on developing the company’s Android app and helped create Cash App.

Lee’s death is being investigated by the San Francisco Police Department’s homicide unit. No arrests have been made and the investigation is active, the police said in its statement.

“Here’s to the crazy ones. We will miss you Bob. We love you,” Goldbard said. “For now, MobileCoin will mourn. We turn our attention to honoring Bob’s legacy by holding his loved ones close.”

Update 4/5/2023, 12:52 p.m. ET: This post has been updated with additional comment from Goldbard and tweets from Shields and Musk.