The quake struck around 12:20 p.m. at a depth of nearly six miles. The epicenter was located in Highland Park.
It originally registered as a 4.7 magnitude earthquake, but was shortly downgraded.
Shaking was felt across the region, from downtown L.A. to Inglewood and as far as Glendora and Hemet.
No damage or injuries were immediately reported, but the L.A. county and city fire departments activated earthquake mode to survey the region for damage.
Seismologist Dr. Lucy Jones provided information on the faults in the area where the earthquake hit.
"This area has a network of buried faults, so it's not something that shows up on the surface. The same network was involved in the 1987 Whittier Narrows quake, but exactly whether it's the same strand, because it's complicated and at depth, we'll never be able to say," Jones said.
Stay with us for the latest details on this developing story.