Los Angeles police and fire officials said there were no immediate reports of damage.
"It rocked and rolled for about 10 or 12 seconds. I'm surprised nothing fell off the walls or broke — and nothing did — but it was quite a shaker," said Brian Bland, a retired AP Radio correspondent who lives in suburban Santa Monica.
The 6:25 a.m. quake occurred at a depth of about 5 miles.
The epicenter was near Sepulveda Pass in the Santa Monica Mountains, about 6 miles from Beverly Hills and 7 miles from Universal City, the USGS said.
All Metro rail lines were expected to experience minor delays this morning as crews inspect tracks for possible damage, according to Metro.
It was one of the largest quakes to hit Los Angeles since the 6.7-magnitude Northridge quake killed several dozen and caused $25 billion in damage two decades ago, Dr. Lucy Jones, a USGS seismologist, told KABC-TV.
"It's not that large by California terms. It's the size of earthquake we have across the state once every couple of months," Jones said. "But we haven't had one like this in LA for quite a while."
A magnitude 4.7 quake struck near Inglewood in 2009, she said.