The quake struck at 1:35 a.m. about 3 miles north of Fontana and 5 miles west of Rialto, according to the U.S. Geological Survey. It said the quake occurred just over 3 miles deep.
There were no reports of any injuries or significant damage, but the temblor was felt across the region, including Fontana, Rancho Cucamonga, Hacienda Heights, Ontario, San Bernardino, West Los Angeles, Downey and parts of Orange County.
Our newsroom was flooded with phone calls with most viewers saying they felt a good jolt and the quake woke them up.
"I was really, really scared. It woke me up out of my sleep so I didn't know what was going on," Fontana resident Raymond Gardner. "We had the wind all night so I figured maybe it was just the wind but I checked the news this morning and sure enough."
"It really opened my shutters up, took some drawers out and woke me up really suddenly. I was scared actually and I'm (a California) native," said Fontana resident Francelle Vercher.
The temblor comes just two days before the 20th anniversary of the magnitude-6.7 Northridge quake that left 57 people dead, more than 5,000 injured and more than $20 billion in property damage.
On Wednesday, an earthquake safety meeting was held in Porter Ranch, just one of many events leading up to the 20th anniversary Friday.
"We have a commitment that the city of Los Angeles is going to look at our science, we're going to work together, put the science together with what the community needs and hopefully make a change," said U.S. Geological Survey seismologist Dr. Lucy Jones.
She says Northridge was a devastating earthquake, but it wasn't the big earthquake.