LOS ANGELES, California - The U.S. Geological Survey said a powerful earthquake with a 6.4 magnitude (downgraded from a preliminary estimate of 6.6) rocked Southern California on Thursday morning during L.A.'s Fourth of July parade.
The biggest earthquake in 20 years to hit SoCal was centered near Ridgecrest in the Mojave Desert at 10:33 a.m. PDT, according to the USGS. People throughout the region reported feeling the quake and reports of scattered damage — including fires and rock slides — rolled in by midday.
"This is a large enough earthquake that it probably did break through to the surface of the earth," USGS seismologist Lucy Jones told reporters. She added that it marked the strongest quake in the region since 1999 when a magnitude 7.1 earthquake struck in a remote part of the Mojave desert.
Jones said the quake was preceded by magnitude 4.2 temblor about 30 minutes before, which she called a foreshock.
Meantime, officials warned that strong aftershocks were expected. Already there had been at least 85 aftershocks — with four large ones recorded measuring 4.7, 3.5, 3.8 and 4.2 magnitude.
"It's certain that this area is going to be shaking a lot today and some of those aftershocks will probably exceed magnitude 5," Jones explained.
Structure fires were reported near the epicenter in the city of Ridgecrest, according to Kern County fire officials who said they were responding to more than 20 incidents relating to the earthquake and aftershocks.
Ridgecrest firefighters could be seen around the city hosing down flames rising from homes.
"As I understand, we have five fires," Mayor Peggy Breeden said. "We have broken gas lines."
The quake sparked evacuations at Ridgecrest Regional Hospital and several apartment buildings, officials said. There were also power outages in the city of 28,000 residents.
Diane Ruggiero, general manager of the Hampton Inn and Suites in Ridgecrest, told CNN that her hotel had suffered significant damage.
"The chandeliers are still swinging," she said five minutes after the quake hit. "The floor rippled."
In nearby San Bernardino County, the quake broke water mains, downed power lines, cracked buildings and caused rock slides on roads. But no injuries or fires were reported, according to fire officials.
Trona, an unincorporated community in San Bernardino, "sustained varying degrees of damage," said Dorothea Smith who indicated that boulders fell down hillsides, shattering the asphalt and blocking mountain roads.
"There is no going in or out of Trona right now. We're like stuck," she said.
Highway 178 has a 4-inch crack, said San Bernardino County Fire spokesman Jeremy Kern. However, all highways in San Bernardino County remained open — and the area's high tension power lines were all intact.
April Rodriguez was at home in Trona when she felt a smaller quake followed by a larger one "that didn't stop," she told CNN.
"We were panicked trying to get out of the house because everything is falling out of the cabinets, off the shelves, off the walls. ... They were flying like missiles off the shelves."
In central Los Angeles — about 150 miles from the epicenter — people said the main temblor was felt as a long, rolling quake that made buildings rock back and forth for at least several seconds. Angelenos noted how rare it was to feel such a long quake.
Movie director Ava DuVernay tweeted, "Been living in Los Angeles all my life. That was the longest earthquake I’ve ever experienced. Not jerky. Smooth and rolling. But it was loooong. It was so long I thought for the first time ever 'Is this the big one?' Damn. Respect Mother Nature. She's the boss."
"This was a strong one, and a good reminder to be prepared," the LAPD tweeted, but the fire department said Los Angeles saw no injuries or significant damage.
At Los Angeles International Airport, crews inspected the runways but didn't find any signs of damage — and flights continued to arrive and depart as normal.
"We have no reports of damage to any FAA facilities or operational effects from the quake at this time," Federal Aviation Administration spokesman Ian Gregor said.
The earthquake was even felt around Las Vegas, Nevada, according to the National Weather Service which added: "So far, no significant damage reports."
A tsunami was not expected, according to the National Tsunami Warning Center.
The most damaging earthquake to ever hit in Southern California was the 1994 magnitude 6.7 Northridge quake in Los Angeles, which caused $25 billion in damage and killed 57 people.