CHENGDU, China — Panic erupted here in the capital of Sichuan Province and at least one other Sichuan city on Monday after provincial television issued a warning of the possibility of a severe aftershock.

Near midnight in Chengdu, thousands of people trying to evacuate the city by car became mired in gridlock, stuck bumper to bumper in clotted streets. Other people quickly gathered blankets and rushed outside, planning to sleep on the street or in neighborhood parks.

In Mianyang, one of the areas hit hardest by last week’s earthquake, guests were evacuated from hotels, joining the masses in the streets. It was not immediately clear on what basis the warning was issued. Hundreds of aftershocks have occurred since the main earthquake on May 12, which the government now says reached a magnitude of 8.0.

The panic occurred hours after the country observed an official period of silence to mourn the tens of thousands of quake victims. At 2:28 p.m., exactly a week after the quake, traffic halted around the country, and millions of Chinese stood with bowed heads and moist eyes. Rescue workers also stopped to honor the dead, marking a pause in a difficult but enormous relief effort as the hopes of finding new survivors faded.

The many powerful aftershocks have hampered relief efforts in Sichuan, located in southwest China. Rain and floods have posed additional threats, forcing some operations to be temporarily suspended. The deaths caused by landslides were reported by Xinhua, the official news agency, but the brief report gave few other details.

Despite the rising death toll, there were a few more remarkable rescues Monday, following a week of small miracles that have been played out on state-run television and have prompted a flood of aid and donations from around the world.

In Beichuan County, a 61-year-old woman who was trapped in debris for about 145 hours was rescued Monday morning, officials said.

But with the confirmed death toll raised to 34,073 by late Monday, and the government saying the figure could reach 50,000, there is more grief than hope here.

Some of the miraculous rescues end in grief, too. After being buried for nearly a week, a 53-year-old woman was pulled from the rubble of a residential building near a coal mine in Hanwang Township on Monday, the government said. But she died in an emergency room later in the day.

For most families, there are only dead bodies and missing relatives, and the odds of finding a relative alive are now small.

To honor those who have suffered, Beijing declared a three-day period of national mourning, beginning Monday.

Flags flew at half-staff and the Olympic torch relay was suspended until Wednesday. In addition, entertainment on television and even online has been curtailed or banned.

On the road to Beichuan, one of the hardest-hit towns, police officers in blue shirts stood with their hats in their hands and heads bowed for the period of mourning.

Several families were trickling back into towns and villages around Beichuan County on Monday, hoping to find any signs of family and friends and survey the damage to their homes.

A group of 12 family members trudged together up the winding road to the town, the county seat. They carried large plastic bags stuffed with clothing and food. Since the earthquake, they had been living in a huge stadium in the city of Mianyang, but now they were making the inevitable trip back to their farming village, somewhere in the mountains.

“We’re just going to take a look,” said Li Zhongying, whose husband was still missing. “Tonight, we’ll sleep wherever we can find a place.”

Her daughter, Li Qingna, 28, walked slowly with a 2-year-old baby in her arms. Her eyes were wet. The walk would take another 10 hours.

Behind them came two men, one from Yunnan Province and the other from Beichuan. They had met on the road earlier on Monday and had been walking side by side since. The man from Yunnan had a wife, daughter and aunt who had migrated here to work at a power plant. He had not heard from them since the earthquake.

That evening, inside the town of Beichuan, four women wailed as they burned incense and paper money in front of a towering pile of rubble. They had returned home today, only to find that their parents had died in a building collapse.

“We wanted to come two days earlier, but we couldn’t get in,” one of the women screamed into the air, her words meant for her parents. “We only got here today!”

There were a few signs of hope, though. Dozens soldiers and rescue workers had gathered atop a mound of rubble in the town center in the late afternoon. They had discovered someone alive in a crevice, more than a week after the earthquake, and were working to get the person out.

At another building, rescue workers piled stacks and stacks of brown folders atop blankets. The folders contained accounting records for the work units in the town and would be crucial to sorting out financial matters. They loaded the folders onto the rear of a bicycle rickshaw and walked them out of the decimated town.

In Mianyang County, people stood for the minutes of silence near the People’s Park. Cars and buses honked their horns, echoing air raid sirens and the sounds of a nation that was otherwise momentarily quieted.

At the Veranda Bridge restaurant in Chengdu, about two hours’ drive from Mianyang, a hundred waiters and waitresses lined up in four rows, and listened to their manager declare, “We are doing this to remember the people who have died.”

And in every part of the country, from Urumqi in the far west, to Hong Kong on the southeast coast, people stood still to remember those who were killed or harmed by the massive earthquake, the worst natural disaster to hit China in more than 30 years.

President Hu Jintao and other top Chinese leaders led the silent tribute from Zhongnanhai, the central government compound in Beijing.

While the nation hangs on stories of remarkable rescues by the more than 140,000 relief and medical workers involved in the rescue, the grim realities of the enormous devastation that has destroyed this region are settling in.

More than 240,000 people have been hospitalized. Many survivors were forced to have limbs amputated. And now, thousands of bodies are being buried and cremated.

Somehow, experts say, an entire region needs to be bulldozed and rebuilt. Hundreds of dams and power stations damaged by the earthquake need repair.

And perhaps most troubling, the government says that about five million people have been left homeless by the earthquake. While huge donations have poured in, totaling over $1.2 billion, many of the survivors say they have nowhere to go.

For the moment, they are living in tents and sports stadiums, reflecting on what has happened to them since that fateful moment last Monday.

“These days I keep going to every hospital in Mianyang trying to find my son,” said Yang Li, 29, who is living in a gymnasium complex and hoping that somehow she will find her 5-year-old boy, Wang Tong Tian, who was in kindergarten when the earthquake struck. “I keep praying we’ll find him. I want my son and I want my home