Philadelphia developers are mourning the sudden loss of Streamline Solutions founder Sean Schellenger, who was pronounced dead Thursday night after suffering a stab wound to the back near Rittenhouse Square. He was 37 years old.

Schellenger was last seen at Rouge, where he was sharing drinks with friends, including former weatherman-turned-developer John Bolaris, according to PhillyMag.

Authorities said an altercation occurred around 11 p.m. at the intersection of 17th and Chancellor streets.

Witnesses said Schellenger was traveling on the passenger side when the Mercedes-Benz he was riding in was stuck in traffic. Three men, including Schellenger, left the car to get a driver in front of them to move, Philly.com reports.

Police said that was when a man on a bicycle instigated a confrontation with Schellenger. When the argument turned physical, the suspect pulled out a large knife, stabbing Schellenger in the back before running away.

Bolaris remembers Schellenger as a friend with a wide smile, and an even bigger heart. He still struggles to comprehend the news, he told Bisnow.

“[Losing] a person like Sean — that kind of bright light, that energy — is a loss to the city,” he said.

An attorney for the driver of the vehicle, restaurateur Norris Jordan, told Philly.com Sunday that only Schellenger got out of the car, and approached the bicyclist, who stabbed him.

The bicyclist, 20-year-old college student Michael White, turned himself in to police early Saturday morning and has been been charged with murder and possession of an instrument of a crime, Philadelphia Magazine reports. A spokesman for his family claimed White was acting in self-defense and that Schellenger, who played quarterback for Penn State University, tackled him.

Schellenger grew up in the Philadelphia suburbs, and according to sources he was determined to succeed due to childhood struggles. He was passionate about Streamline Solution’s multifamily developments, affordable housing and helping others.

“He always wanted to help people who couldn’t afford the homes they needed. He understood the hard times," Bolaris said. "Whether you’re working on a deal at $100K to a multimillion-dollar deal [with Sean] — he was always the same. I don’t know how to end it because it wasn’t supposed to end like this."

This incident is the latest in a spiked increase in homicide rates in Philadelphia. There have been 165 people killed in 2018.

Those with any information are asked to please submit a tip to 215-686-TIPS (8477).

UPDATE, JULY 16, 1:45 P.M. ET: This story has been updated with the latest information about the incident.