Medics rushed to Chico's Barnes and Noble book store late Thursday afternoon, after witnesses watched an unresponsive man dumped from a vehicle right in front of the store.
It happened around 5 p.m. at the store on Dr. Martin Luther King Jr. Parkway in South Chico.
Police said the middle-aged man was unresponsive, and his heart stopped beating.
Medics performed CPR and rushed him to Enloe Medical Center. His condition is unknown.
Witnesses told police someone in a silver Jeep Cherokee had removed the man from the SUV, left him lying on the sidewalk, then drove off. Police are still looking for that vehicle.
Investigators are investigating it as suspicious circumstances. They don't know if the man was assaulted, or may have suffered a medical condition.