The incident started around 7:30 p.m Wednesday when officers confronted a man in the parking lot of an AutoZone on Foothill Boulevard and Mango Avenue, according to authorities.
They were conducting a traffic stop on a vehicle that was believed to be involved in an earlier incident involving someone brandishing a firearm.
Police say the driver ran away on foot and officers chased after him. It's not clear exactly what happened next but the department says "The situation escalated, resulting in the use of force, including the discharge of firearms by officers."
The man was injured and then brought to a local hospital, where he was later pronounced dead.
The man's identity has not been released, pending notification of next of kin.
Police say a gun was recovered at the scene of the shooting.
No officers were hurt.
The San Bernardino County Sheriff's Department is conducting a review on the lethal use of force, while the Fontana Police Department is also conducting its own internal review of the incident.