People inside two cars exchanged gunfire with each other in San Francisco Sunday morning before fleeing the scene, according to police.

No injuries were reported, and police have yet to locate any suspects or victims following the shooting, which occurred along the 2700 block of Polk Street around 9:30 a.m., according to San Francisco Police Department spokesperson Giselle Talkoff.

Officers spotted shell casings on the ground, and nearby car windshields were pierced with bullets.

The violence stunned and worried neighbors. One man described what he heard.

"Well, I woke up and was trying to grab a cup of coffee and heard something that I thought was a firecracker, and then heard another one, and there was about 12 in total," neighbor T.J. Ross said. "I literally hit the deck after about the sixth one."

"Well, it scares me," resident Julie Pearson said. "There have been other occurrences on the street so it makes me nervous."

A motive was not clear to investigators Sunday, and no arrests have been made, according to police. The investigation is ongoing.