The quake struck at 5:35 p.m. and was centered about 5.6 miles southeast of Upland, according to the U.S. Geological Survey. Its epicenter was measured at a depth of 2.85 miles.
ABC7 viewers said they felt the seismic event in Chino, Riverside and Eastvale.
"No shaking just sounded like a boulder hit the ground in Rancho Cucamonga," Frank Gonzalez said on Twitter.
There were no immediate reports of injuries or damage.