LUSHAN, China (CNN) -- Families badly in need of food and water are living in makeshift shelters near the shattered remains of their houses in this area of the southwestern Chinese province of Sichuan where a strong earthquake struck over the weekend, killing at least 192 people.
In the race to find survivors in the rubble before it is too late, rescue workers are having to contend with frequent aftershocks that threaten to set off landslides and topple more buildings.
Some of those who evaded the tumbling debris when the quake hit on Saturday are now taking refuge under lean-to tents; others have no shelter at all. In many cases, it's too dangerous to go back inside the precarious ruins of their heavily damaged houses to look for food and belongings.
Chinese authorities have marshaled a big response to the disaster, trying to meet the basic needs of the tens of thousands of people left homeless in Sichuan, which five years ago suffered a devastating earthquake that killed more than 87,000 people.
With many reservoirs in the area damaged, the Sichuan Red Cross has expressed concern that drinking water in the city of Ya'an, a hilly area of Sichuan that bore the brunt of Saturday's quake, could run out in the coming days despite efforts to deliver supplies
Xinhua reported Sunday that some of the water supply in Lushan County, the district where the quake's epicenter was located, had been restored, providing about 100,000 residents with water for emergency use.
But right now the focus is on recovering survivors before the closure of the crucial 72-hour window in which rescue workers hope to find people alive after natural disasters.
"The top priority is to save lives," Ma Jun, the head official of Baoxing County, one of the hardest hit areas, told the state-run news agency Xinhua. "Meanwhile, we'll resettle the residents and reopen roads."
Volunteers and family members were reported to have joined the search.
More than 2,000 aftershocks -- some of them were stronger than magnitude 5.0 -- have rattled the area around the epicenter of the original quake, which ripped huge chunks of rock out of the sides of mountains, state-run media reported.
The massive boulders that tumbled into valleys have made it harder to reach some of the most severely affected areas. The original quake Saturday was put at a magnitude of 6.6 by the U.S. Geological Survey and 7.0 by Chinese seismologists.
The death toll from the quake stands at 192, with more than 11,000 injured, Xinhua reported Monday, citing Sichuan's emergency response center. Twenty-three people are still missing, it said.
Local officials have cautioned that because of the scale of the destruction and the disruption to communications, determining the total number of casualties will take some time.
Chinese Premier Li Keqiang has visited the area. He spent Saturday in Lushan, directing the response near the quake's epicenter, Xinhua reported, then visited hospital patients Sunday.