A rock slide took place in Carbon Canyon, about six miles from La Habra.
Video showed a white car flipped over on its roof, apparently by the rock fall. The driver escaped with no major injuries, according to CBS 2 television.
At Dodger Stadium, the quake briefly interrupted the baseball game between the LA Dodgers and the Angels.
A power outage attributed to the quake cut electricity supplies to nearly 2,000 customers in the La Mirada area, near La Habra, said a spokeswoman for the Southern California Edison utility company.
Ring of Fire
California has long braced for the "Big One."
The state is on the so-called Ring of Fire, which circles the Pacific and has produced a number of devastating quakes including Japan's March 2011 quake-tsunami, which killed thousands of people.
Seismologists say a quake capable of causing widespread destruction is 99 percent certain to hit California in the next 30 years.
A 6.7-magnitude earthquake in 1994 in Northridge, north west of LA, left at least 60 people dead and caused an estimated $10 billion damage, while a 6.9 quake in San Francisco in 1989 claimed the lives of 67 people.
USGS seismologist Robert Graves said southern California has had a relative "drought" of earthquakes over the last two decades, which might be ending.
"We might be getting back to the more normal rate before the Northridge earthquake happened," he said. "It means it was quiet, but it's not quiet now."