Cash App founder Bob Lee died on Tuesday after being stabbed around 2:35 a.m. in San Francisco, ABC News reported. Police said they responded to a report of a stabbing and found a 43-year-old man who sustained life-threatening injuries after being attacked in the streets of downtown San Francisco. Lee died after he was taken to a hospital.

Rick Lee, Bob’s father, confirmed the news in a statement on Facebook.

“I just lost my best friend,” he said, adding that his son “lost his life on the street in San Francisco early Tuesday.”

San Francisco mayor London Breed also expressed his condolences, CNN reported.

“My sympathies go out to his family and friends,” he said. “The police are actively investigating what happened and will share details as soon as they can.”

Before he founded Cash App, Lee served as the first chief technology officer of the digital payment company Square. He also worked at Google, where he helped develop Android.

Additionally, Lee was working as the chief product officer of the cryptocurrency company MobileCoin, NBC News reported.

“Bob was a dynamo, a force of nature,” Joshua Goldbard, the CEO of MobileCoin, told ABC News in a statement. “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.”

Lee was raising two children with his wife Krista.

“Bob’s real resume is the hearts and minds he touched in his time on earth,” Goldbard said. “Bob’s legacy is the feeling that you can make a difference if you try, and of course his amazing children.”