Bob Lee, chief product officer of crypto startup MobileCoin, has died after being attacked in San Francisco.

The San Francisco Police Department said on its website that officers found a 43-year-old man with stab wounds after responding to a call at 2.35 am, and the person later died at the hospital.

A spokesperson for the SFPD declined to release further information when contacted by Bloomberg because the homicide is an active investigation. The San Francisco Chronicle first reported Lee’s stabbing.

Lee is survived by “a loving family and collection of close friends and collaborators,” MobileCoin chief executive officer Joshua Goldbard said in a statement on Wednesday.

“Bob was made for the new world, he was the quintessential creator, leader, and consummate hacker,” Goldbard said. “Bob surely had an impact that will last far beyond his short time on earth.”

Lee was the first chief technology officer of Square, the financial technology startup co-founded by Jack Dorsey, and now called Block Inc. While at the company, he created CashApp, a money transfer app that also lets users buy stocks and Bitcoin. Earlier in his career, he helped develop Android while he was a software engineer for Google.

“Heartbreaking,” Dorsey wrote on social media platform Snort. “Bob was instrumental to Square and Cash App.”

Figma CEO Dylan Field recalled Lee’s early support of his company and wrote on Twitter, “It’s so hard to believe he’s gone.”

Lee’s work on Android and then Square made him a “mythical figure” to young tech workers beginning their careers, said Max Rhodes, who joined Square in his early twenties and worked closely with Lee on Cash App.