A runaway U-Haul truck killed a man who had been piloting the truck in the Tenderloin on Tuesday, but some quick thinking by the victim's grandson may have saved multiple other lives.

An alert went out on the city's emergency system just before 12:30 p.m., telling drivers to avoid the area of Geary and Jones streets, due to a vehicle collision.

As KRON4 reports, the collision took the life of one pedestrian.

SFPD officers said they arrived at the scene after receiving a report of a person struck at 12:13 p.m. At the scene, they found a man fatally injured in the street. He later died at an area hospital.

The victim, as KTVU reports, had been in the driver's seat of the U-Haul truck when, apparently, its brakes gave out while on the slope of Jones Street. Police are still investigating what happened with the truck, but it reportedly rolled out of control down Jones Street toward Geary, and the man "somehow got out of the vehicle while it was moving, and was hit."

The two men were reportedly helping someone move on Jones Street. The man in the passenger seat of the truck, the victim's grandson, managed to steer the truck into a parked FedEx truck, avoiding letting the truck continue rolling out of control through more intersections.

"As the truck began rolling he was able to kind of steer it away from pedestrians," says Lt. Mark Moreno from the SFPD, speaking to KTVU. "I don't know how many people were on the street at the time, but he was able to steer it away from pedestrians and other cars and into that truck."

Video shared on the Citizen app showed the crash scene, showing a U-Haul truck in the crosswalk, having crashed diagonally into the parked FedEx truck by the curb.

Person Critically Injured After Being Hit by Truck @CitizenApp

Jones St & Geary St 12:16:25 PM PDT

Lt. Moreno tells KTVU that SFPD traffic investigators were on the scene attempting to determine what had happened, adding that this was "kind of a higher, more complex investigation" that involved "doing the measurements taking photographs... Trying to gather video surveillance."

Subsequently, at 2:30 p.m., there was a report of an ambulance — possibly an SF Fire Department EMS vehicle — involved in a crash at Fulton Street and Arguello Boulevard.

This post has been updated throughout following KTVU's report.

Top image via Citizen app