LOS ANGELES (CBSLA.com) — A 4.4-magnitude earthquake and at least six aftershocks shook the Sepulveda Pass area Monday morning.

The tremor struck at 6:25 a.m. and was “epicentered in the Santa Monica Mountains between Westwood and Encino, closer to the Valley side, about five miles below the surface,” Dr. Lucy Jones of the U.S. Geological Survey said.

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Residents felt the quake in Los Angeles, Ventura, San Bernardino and Orange counties.

Monday’s tremor was the largest earthquake in Los Angeles since the region stopped having aftershocks from the 1994 Northridge quake, Jones said.

“I thought, you know, it was like a car smashing into the station or something,” gas station employee Magdalena Murillo said. “It was shaking the window, and I was like ‘what’s going on’, and I’m by myself. It was frightening.”

The quake was initially measured at a 4.7-magnitude, but was downgraded minutes later by the USGS to a 4.4-magnitude.

The Los Angeles Fire Department was in earthquake emergency mode as crews surveyed the city by ground and air, however, there were no reports of any earthquake-related injuries or damage.

Jones said it was likely that the region would feel aftershocks throughout the day, including a 2.7-magnitude quake that struck around 7:23 a.m.

USGS officials said there was a five percent chance Monday’s quake could be followed up by a larger earthquake within three days.

“The chance we’ll get a bigger one is now probably 1-in-30 or 40, something like that,” Cal Tech seismologist Tom Heaton said.

An early warning system, currently being pioneered by Cal Tech, is designed to give a two-second warning that an earthquake is on the way, along with the expected severity of the quake. Heaton got to experience the system first hand Monday morning.

“I was sitting there at breakfast, and my laptop computer told me that shaking was coming, and then I felt it, and it was nice,” Heaton said. “We all know the drill; you feel the shaking, and you don’t know if it’s going to get bigger or smaller. (With) a system like this, you know instantly that it’s not going to get bigger. It’s just a routine Southern California earthquake.”

For more information on earthquake safety or preparedness, visit Red Cross LA or PrepareSoCal.