BEIJING - The collapse of a bridge under construction that left at least 36 people dead in a Chinese tourist town rekindled concerns Tuesday about rushed, shoddy building amid the country's economic expansion.

Witnesses heard a rumble and saw stones fall from the structure Monday afternoon after construction workers removed scaffolding from the 42-metre-high, 268-metre-long vehicle and pedestrian bridge across the Tuo River in the southern town of Fenghuang.

"The whole thing collapsed," said Nong Xiaozhong, one of two survivors in a 12-man construction team working under the bridge.

"There was no time to warn the other workers and I just managed to run a few steps before I was covered under the stones," Nong said in a telephone interview from the Fenghuang Chinese Medicine Hospital where he was being treated for pain in his abdomen. "I crawled to the road nearby and an ambulance came in 10 minutes. I was rescued."

The accident came less than two weeks after the collapse of a bridge in Minnesota that drew attention to aging transport infrastructure in the United States. Nine people were confirmed dead in that collapse, and divers are still seeking the bodies of four missing motorists presumed killed.

In China, rescuers managed to save 86 people, including 22 who were injured, many from the 123 workers on the site at the time of the collapse, the government's Xinhua News Agency reported. The death toll rose steadily as rescuers with trained dogs and bulldozers sifted through mounds of toppled concrete. Seven bodies were found early Wednesday, said Li Ping, a local government spokesman. He said he did not know how many people were still unaccounted for.

Police detained two officials from the builder, the state-owned Hunan Road and Bridge Construction Co., Xinhua said, even as the Work Safety Administration of Hunan province, where Fenghuang is located, said the accident's cause was under investigation.

The collapse was likely to fuel already deep public concerns about the quality of construction in a country undergoing breakneck economic development and where corruption among contractors and officials is common.

The state-run China Daily, in a report Tuesday, said that the Ministry of Communications last year deemed 6,300 bridges as dangerous because of serious damage to their "structural components." It quoted a prominent engineer as warning that many new bridges were poorly designed and built and that China needed to heed the Aug. 1 collapse of a bridge in Minnesota that killed at least nine people.

China should "learn a lesson" and accelerate the inspection of unsafe bridges, the newspaper quoted Xiao Rucheng, secretary-general of China's Institute of Bridge and Structural Engineering, as saying.

Premier Wen Jiabao called for a thorough investigation into Monday's collapse, saying those responsible would be "severely dealt with."

Fenghuang -- an ancient trading town surrounded by lush mountains and rice paddies, and known for the colorful dress of its Miao, or Hmong, ethnic natives and its traditional stilt houses along the Tuo -- has aggressively promoted itself as a tourist destination.

Nong, the construction worker, said that he and his fellow workers worried that the bridge's stone arches were too large and that the mortar was not dry enough to remove the scaffolding. "But after all, we trust those engineers," he said.

When the bridge collapsed, "there was a huge amount of dust that came up and didn't clear for about 10 minutes," said a witness, a cleaning lady at a local hotel who gave her surname as Wu and said she had just passed under the bridge on a bicycle when the span fell.

China Central Television showed bulldozers plowing through the rubble, overturning chunks of stone and concrete mixed in a tangle of steel reinforcement bars.

Xinhua described a grim scene of bodies being pulled from the toppled concrete. "Their arms and legs were broken, only linked with skin," Xinhua quoted Yang Long, a villager whose home was just a dozen yards from the site, as saying.

The Fenghuang collapse is among the worst in recent memory. On June 15, a bridge over the Xijiang River in south China's Guangdong province collapsed when a cargo vessel loaded with sand rammed into it, killing nine people.

In January 1999, 40 people died when a pedestrian bridge spanning the Qi River in southwestern China's Sichuan province collapsed just three years after it was built. In that case, a local party secretary was sentenced to death for accepting a bribe from a childhood friend in exchange for the bridge-building contract.