USGS said the quake was centered about 3.7 miles north-northwest from Pedley and 4 miles east-northeast from Riverside when it hit at approximately 3:03 a.m.
The depth of the temblor was about 3 miles.
A USGS map showed the shaking was felt over a region stretching from Rancho Cucamonga to near the Perris area, and from Chino to Moreno Valley.
There were no immediate reports of injury or damage.