The quake occurred at 11:27 a.m. and was centered about 3 miles east-southeast of Loma Linda, at a depth of about 9 miles, the USGS said.
There were no immediate reports of injuries or damage.
ABC7 viewers said they felt the earthquake in Riverside and Colton.
"It was a fast, hard shake for me. I'm in Northern San Bernardino," Krystal Mead said on Twitter.
Others, like Kevin Burke, were dismissive of the relatively small temblor.
"We're reporting 3.5 quakes now?" he tweeted.