San Francisco, California - Tech executive Bob Lee, who founded the mobile payment service Cash App, was killed in a stabbing in San Francisco, according to authorities and media reports.

Police responded Tuesday at about 2:35 AM local time to a report of a stabbing and found a 43-year-old man suffering from wounds.

After paramedics were called to the scene, the man was taken to a hospital, where he died, police said. The attack is under investigation, and no arrests have been made.

Police declined to provide further information, citing the ongoing investigation, but multiple media outlets have reported that Lee, who was chief product officer at cryptocurrency startup MobileCoin, was the victim.

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The killing reignited concerns from some high-profile figures over public safety in San Francisco, where a progressive district attorney who had become a lightning rod for controversies over crime and homelessness was recalled by voters last year. His replacement, Brooke Jenkins, said upon her appointment that San Francisco was "at a tipping point."

"I want to extend my sincerest condolences to Mr. Lee's family members & loved ones for his loss," San Francisco District Attorney Brooke Jenkins tweeted Wednesday. "We do not tolerate these horrific acts of violence in San Francisco."

Reactions from the tech world included Twitter CEO Elon Musk, who expressed condolences to a friend of Lee's and asked Jenkins whether the city is "taking stronger action to incarcerate repeat violent offenders" – even though it's not yet clear whether the person who attacked Lee already had a criminal history.

Later Wednesday, Jenkins updated her statement on Twitter, saying "holding violent/repeat offenders accountable is a top priority for my administration."

"No one who commits a violent crime, or who's a repeat offender are receiving overly lenient plea deals," Jenkins said.

Lee's friend, mixed-martial artist Jake Shields, wrote on Twitter that Lee "was in the 'good' part of the city" when he was stabbed, on a block near luxury condominium complexes and many office buildings, including Salesforce Tower and Google's San Francisco offices.