LA HABRA -- A magnitude-5.1 earthquake centered 2 miles east of La Habra late Friday rattled buildings and ruptured gas lines throughout Los Angeles County, officials said.
The quake was reported at 9:09 p.m. according to data from the United States Geological Survey. The shaking originated about 5 miles underground.
The 5.1-magnitude quake was followed two minutes later by another quake of magnitude 3.4, officials said.
Reports of natural has leaks began flooding in to officials once the shaking stopped, Los Angeles County Fire Department Dispatch Supervisor Ed Pickett said.
"We've got reports of lots of gas leaks in the Rowland Heights and La Habra areas," he said.
Authorities were still working to assess and attend to the damage, Pickett said.
The earthquake sent rocks tumbling onto the Holt Avenue offramp of the westbound 10 Freeway in Covina, creating a traffic hazard, according to CHP officials. No other earthquake damage had been reported to the CHP late Friday.
Shengzao Chen, a USGS geophysicist, said his office had not heard of any immediate damage or injury reports.
"Right now, it's pretty good," Chen said. "But we have to keep our eyes open to see what's going on. The magnitude is 5.1 which is not big or small, it's a middle quake. It's also a shallow quake."
There were more than a dozen aftershocks following the 5.1 magnitude quake, with magnitudes as high as 3.6, according to the USGS.
Claremont police Lt. Shelly Vander Veen said there was no reported damage on Friday night in Claremont.
"We felt the same thing everyone else will say -- a jolt," Vander Veen said.
Officials in Pasadena surveyed the city following the quake and found no signs of injury or damage, Pasadena Fire Department officials said.
The larger quake was preceded by a magnitude-3.6 earthquake reported in the same area, about 1 mile southeast of La Habra, according to seismologists at Caltech in Pasadena.
The smaller tremor occurred at 8:03 p.m. with an epicenter about a mile southeast of La Habra, according to a statement issued by Caltech. That quake's depth was initially reported to be about 4 miles below the surface.
Looking forward, seismologists estimated the likelihood of another quake stronger than the original 5.1-magnitude shock over the next seven days at 5 to 10 percent, according to the USGS.
"Most likely, the recent mainshock will be the largest in the sequence," the agency said in a written statement.
The chance of "strong" aftershocks -- those with a magnitude of 5 or greater -- over the next week was estimated by USGS seismologists at 10 percent.
Aftershocks with magnitudes ranging from 3 to 5 are expected to be relatively common over the coming days.
"Approximately three to 20 small aftershocks are expected in the same seven-day period and may be felt locally," according to the USGS statement.