And a magnitude 1.8 quake hit the same approximate area at 12:51 p.m., according to early, automated reports. Originally reported by automated sensors as magnitude 2.1, its epicenter was near La Brea at Slauson avenues, in the Baldwin Hills just north of Inglewood.
No damage or injuries were reported from either shaker.
After the magnitude 3.9 pre-dawn quake, the Los Angeles city Fire Department declared the area safe. It had surveyed a 478-square-mile area spanning 106 neighborhood fire stations, spokesman Erik Scott said.
They were the third and fourth temblors within the past month near the Newport-Inglewood fault. A magnitude 3.5 quake was recorded there on April 12 and a 3.4 on April 30.
USGS officials consider Sunday's 4:07 a.m. shaker relatively shallow and said it was not severe enough to cause major damage.
But that didn't stop shaken Los Angeles area residents from taking to social media to verify the earthquake and share their experiences.
Most described a loud, sudden jolt, followed by a rolling or rocking sensation.
"I knew it was Baldwin Hills cause my house felt like it was on an electric bull,'' one person wrote.
"Shaken awake by a nearby 3.9 along the Newport-Inglewood Fault in Baldwin Hills. Get prepared SoCal,'' wrote another.
But with Nepal still recovering from a 7.8 earthquake on April 25 that left more than 7,000 people dead, some felt Angelenos should keep their jitters in check.
"Baldwin Hills is trending because of a 3.9 earthquake?'' one woman posted. "I would like to apologize to Nepal for this nonsense. Sorry.''
Dr. Lucy Jones, a seismologist with the USGS in Pasadena, said the Baldwin Hills area has experienced major earthquake activity every year since a magnitude 4.7 quake on May 18, 2009.
"Little earthquakes happen all the time,'' she posted, "and we can't find a significant pattern.''
Experts have also rejected amateur theories floating around, that the quakes were related to fracking in the Baldwin Hills oil fields, or to subway digging on Crenshaw Boulevard.