MEXICO CITY -- A strong new earthquake shook Mexico on Saturday, causing new alarm in a country reeling from two still-more-powerful quakes this month that have killed nearly 400 people.

The U.S. Geological Survey (USGS) said the new, magnitude 6.1 temblor was centered about 11 miles south-southeast of Matias Romero in the state of Oaxaca, which was the region most battered by a magnitude 8.1 quake on Sept. 7.

It was among thousands of aftershocks recorded in the wake of that earlier quake, the most powerful to hit Mexico in 32 years, which killed at least 90 people.

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The new quake also swayed buildings in Mexico City, which is trying to recover from a magnitude 7.1 temblor that struck on Tuesday, killing at least 295 people.

The USGS said "some casualties and damage are possible and the impact should be relatively localized."

Police officers and people wait along the street after a tremor was felt in Mexico City, Mexico, on Sept. 23, 2017. HENRY ROMERO / REUTERS

There were some early reports of damage. Bettina Cruz, a resident of Juchitan, Oaxaca, said by phone with her voice still shaking that the new quake felt "horrible."

"Homes that were still standing just fell down," Cruz said. "It's hard. We are all in the streets."

CBS News correspondent Manuel Bojorquez reports that seismic alarms sounded in the Mexican capital. The aftershock swayed buildings and prompted civil defense officials to temporarily suspend rescue operations in the rubble of buildings downed by Thursday's quake.

The quake was much weaker than the quake that hit on Tuesday, killing at least 295 people and knocking down buildings across the capital.

As rescue operations stretched into Day 5, residents throughout the city held out hope that dozens still missing might be found alive. More than half the dead -157 - perished in the capital, while another 73 died in the state of Morelos, 45 in Puebla, 13 in Mexico State, six in Guerrero and one in Oaxaca.

Along a 60-foot stretch of a bike lane in Mexico City's downtown, families huddled under tarps and donated blankets Friday, awaiting word of loved ones trapped in the four-story-high pile of rubble behind them.

This is a developing story.