MEXICO CITY _ A new earthquake sent Mexico City residents streaming onto the streets early Saturday, creating more alarm in a country still trying to recover from two powerful earthquakes over the past three weeks.
The U.S. Geological Survey said Saturday's magnitude 6.1 earthquake, which hit just before 8 a.m., was centered about 12 miles southeast of Matias Romero in the state of Oaxaca, the region that took the brunt of the magnitude 8.1 quake Sept. 7.
Saturday's earthquake was probably an aftershock of the Sept. 7 quake, Mexican officials said.
Authorities have registered more than 4,000 aftershocks from the Sept. 7 quake, but Saturday's appeared to be the strongest.
There were no immediate reports of major new damage or casualties in the Mexican capital, but in southern Oaxaca state, authorities said the strong aftershock caused new damage to homes and other structures already weakened by the Sept. 7 quake.
That quake killed 300 dead and left multitudes homeless, while damaging thousands of buildings in Mexico City and neighboring states.
The earlier Sept. 7 quake killed nearly 100, mostly in Oaxaca and neighboring Chiapas state.
Quake alarms sounded throughout Mexico City Saturday, and spooked residents dashed from homes and hotels. Many remain on edge here since Tuesday's devastating quake. Electrical cables shook and some buildings swayed.
But most of the damage appeared to be centered closer to the quake, in the state of Oaxaca.
Homes tottering from the Sept. 7 earthquake showed new cracks and in some cases collapsed in the city of Juchitan, the principal municipality on the Isthmus of Tehuantepec. Thousands of people who had to evacuate their homes there on Sept. 7 have been living under plastic tarps.
Outside Juchitan, in the hard-hit town of Asuncion Ixtaltepec where 80 percent of residences were rendered uninhabitable on Sept. 7, some homes fell or showed new fissures.
A bridge that had been damaged by the earlier quake was split in half and teetering on the verge of collapse following Saturday's aftershock.
Damage was also reported at a nearby military airbase that has been a central point for deliveries of food and other aid to Oaxaca. A hospital was evacuated in the port city of Salina Cruz in Oaxaca state.
Authorities in the city of Oaxaca, the capital of Oaxaca state, reported only minor damage, including cracks on the bell tower of a colonial era church.
In Mexico City, officials temporarily suspended rescue operations that have been ongoing since a 7.1 magnitude earthquake struck the capital Tuesday. The suspension was to give specialists time to evaluate any new risks.
"People are paranoid, nervous, they don't know if they can stay at home in any moment or have to run out," said Mayela Ruiz, one of a number of volunteers handing out food, clothing and other basics in the Condesa district, which was extensively damaged in Tuesday's quake. "One's feelings go from panic to nervousness in a moment."
Saturday's quake was felt lightly in the Condesa neighborhood, parts of which have a near-abandoned feel since thousands left their shaky homes. Some cafes and restaurants reopened Saturday, only to have panicked diners rush out the doors.
Guadalupe Guarrdarama went out in the street crying, wondering if a building near her home that has been on the verge of collapse from Tuesday's earthquake would finally fall.
Guarrdarama works in a restaurant in the Mercado Medellin in the Roma neighborhood. After the initial quake Tuesday she struggled to breathe as others tried to calm her down. She's felt a heavy weight sitting on her chest ever since and has begun to wonder if she needs to speak to a psychologist.
"I feel anxious, I don't feel safe," she said.
"I feel anguished, afraid," said Angelica Salas, who was at home in the Roma neighborhood when the aftershock occurred. "I thought the house would fall last time, so you think the same thing."
Emergency workers have been searching the ruins of at least eight collapsed buildings in the capital for survivors. They must sift through fragile piles of rubble that can pose a danger of collapsing anew.
At least 30 people are believed to be missing in the rubble, Mexico City Mayor Angel Mancera told Mexican television. He and other officials have said rescue work would continue until everyone is accounted for, even as chances of survival in the rubble dim as time passes.
About 3,000 structures in Mexico City suffered damage and close to 40 buildings collapsed in Tuesday's quake, authorities have said.
