The quake struck at 6:25 a.m. two miles south-southeast of Encino. It was first reported as a 4.7, but it was quickly downgraded to a magnitude 4.4.
"It was about two jolts. The first one and the second one hit pretty simultaneously," said Kevin Cook of West Covina.
The earthquake had a depth of 5.3 miles, and shaking was felt in Santa Monica, Brea, Riverside and Palmdale, and strongly felt at the ABC7 station in Glendale.
Seismologists called Monday's event a minor to moderate quake, but what was surprising to them was that the epicenter was the Santa Monica Mountains. This quake was the only one of its magnitude recorded in that area.
The quake confirmed that Caltech's experimental early-warning system is working. Seismologists got a two-second warning that the earthquake was coming. Their goal is to receive at least a four-second alert.
"If I was in the office, I could duck under my desk. If I was a computer controlling an elevator, I could bring it to the nearest floor," said Egill Hauksson, a seismologist at Caltech.
Kelly Jackson of Woodland Hills says it was her first earthquake since she moved to the area three years ago.
"I thought it was the apocalypse. I looked at my daughter and started screaming, I'm not kidding," Jackson said with a laugh. "It felt like it was 20 hours of my life."
There were no reports of injury. The quake didn't do a lot of damage, but it did do some. One viewer from Bell Canyon, near West Hills, sent in a photo of a broken window.
Several aftershocks were felt after the initial earthquake, including a 2.7 magnitude that struck at 7:23 a.m.
"Today's earthquake is a reminder that every L.A. family must be prepared with food, water and other essentials, as well as a plan," said Los Angeles Mayor Eric Garcetti in a statement. "While it appears the greatest impact of this temblor was a rude awakening, we are executing our post-earthquake protocols to survey our neighborhoods and critical infrastructure."
A Metro spokesperson said all rail lines were expected to experience minor delays as crews inspect tracks for possible damage.