BOSTON — Blue lights and sirens ripped through Back Bay Tuesday night after a food delivery stop spiraled into a road rage stabbing that left a man bleeding and collapsing outside the Westin in front of stunned hotel guests.

Police say it began just after 10:30 p.m. on Beacon Street, when the victim and a passenger briefly parked in front of another car while delivering food. The driver of that car — now identified as 45-year-old Byron Alexander of Randolph — allegedly snapped, leaning on his horn before tailing their vehicle through the neighborhood.

According to investigators, Alexander tried to ram the victim’s car. At a red light, he jumped out, confronted the driver, and stabbed him multiple times in the chest before fleeing.

The victim managed to drive to Huntington Avenue, pulling up near the Westin Copley. Witnesses watched in horror as the SUV rolled to a stop, the man stumbled out, and collapsed in a bloody heap. Within seconds, the street was flooded with flashing lights — cops shouting, medics sprinting, ambulances pushing code red.

Scanner chatter captured the chaos, with dispatchers begging the victim to stop and wait for paramedics. He ignored them, tearing through Boston’s glitzy blocks while bleeding out behind the wheel.

State Police later spotted the suspect’s car barreling down I-93 South and boxed him in near Freeport Street. Alexander was pulled out and cuffed on the spot. He is expected to be arraigned in Boston Municipal Court on charges of Assault and Battery with a Dangerous Weapon.

The victim was rushed to the hospital with what police now say are non-life-threatening injuries.

Back Bay’s polished façade was left shattered — a neighborhood of brownstones and brunches transformed into a war zone of sirens, flashing blue, and a stabbing over nothing more than a horn blast.