Updated

Two of Asia's most dynamic and fast-growing cities were struck within hours by disasters that devastated a pair of apartment blocks and underscored the challenges faced by both China and India as they try to enforce safety and building codes amid torrid economic growth.

In Shanghai, welders apparently ignited a blaze that engulfed a high-rise, while in New Delhi it might have been monsoon rains or an illegal new floor that caused the building's collapse Monday. The two tragedies, thousands of miles (kilometers) apart, killed at least 119 people.

Indian and Chinese cities have expanded at breakneck speed over the last few decades, buoyed by growth that has swelled the middle class and brought waves of rural migrants seeking better opportunities. The pace and scale of the building boom has been head-spinning, and is not expected to slow soon.

Investigators looking into Monday's blaze in Shanghai say unlicensed welders misused their equipment, accidentally starting the fire that quickly engulfed the 28-story apartment building. Police detained eight people Tuesday as they investigated the blaze that killed 53 and sent 70 to hospitals.

In New Delhi, the five-story building pancaked, killing 66 people and injuring scores. Neighborhood residents said the landlord was adding an unauthorized floor to the 15-year-old building to pack in more migrant workers and their families. An official said monsoon rains may have weakened the structure.

Maria Chen, China representative for ICF International — a management and technology consulting company based in Fairfax, Virginia, that helps companies in China become more energy efficient — said the rapid pace of construction inevitably leads to disasters such as the fire in Shanghai.

"Part of the problem is just the scale of magnitude," said Chen. "Every year China is putting up 2 billion square meters (2.4 billion sq. yards) of new building space ... That's 50 times Manhattan's office stock. So China is putting that many buildings on the ground, quickly, and with minimal (safety) enforcement. That's really one of the overarching problems — and also developers desire to make quick money."

India and China have produced high growth in sharply different ways. China's more government-directed capitalism excels at topdown directives and mammoth infrastructure projects. India's urbanization has been more chaotic with greater scope for private entrepreneurship. But they are both running up against basic problems in their race to modernize: shoddy construction, lax enforcement of building codes, and rampant corruption.

In India, the result has been glass and steel high-rises and thickets of crowded low-rise buildings and shanty towns. Callous building contractors flout existing laws while unscrupulous government officials ignore illegal constructions of poor quality that meet the soaring demand for cheap housing.

With land prices spiraling out of control in New Delhi, builders stack additional floors onto their buildings without getting the required clearances or by paying bribes to get officials to turn a blind eye — which residents alleged is what happened in Monday evening's disaster.

The building, housing hundreds of people, was located in the city's congested Lalita Park area. Emergency efforts were hampered because vehicles had difficulty navigating the neighborhood's narrow alleyways.

Officials ordered the evacuation of at least one other nearby building with a flooded basement that they feared could collapse.

In China too, real estate prices in mega-cities such as Beijing and Shanghai have spiraled, yet residents often worry about the integrity of new gleaming buildings that are built fast and with little apparent attention to quality.

Last year, a nearly finished 13-story apartment building in Shanghai collapsed. Excavations for an underground parking garage may have undermined the structure, causing it to topple.

Ambitious government plans to renovate old buildings to make them more energy efficient — and reduce China's greenhouse gas emissions, the world's largest — are also adding to the construction frenzy.

Shanghai's fire chief told reporters during Monday's fire the flames raced along a scaffolding of bamboo and flammable nylon nets — erected to retrofit the 1990s-era building with more energy-efficient insulation.

"With the quick pace of building construction in China, there's great need for construction workers. However, the quality of these workers is a big problem these days," said Li Hua, an engineer and researcher with China Academy of Building Research.

"Now most of these jobs are given to migrant workers who have little or no training at all and generally neglect safety codes," Li said. Projects are also routinely subcontracted several times, weakening oversight and accountability, he added.

Graft may also have contributed to the building collapse in New Delhi. "It's because of the corruption. The government officials and city officials, they all take bribes and allow more floors to be built and you have this result," alleged Pankaj Kapoor, a resident.

The Press Trust of India reported Tuesday evening that police arrested the building's owner, Amrit Singh, who residents said had fled the area.

Rocketing real estate prices play a part in such tragedies, crowding out affordable, legal housing, said Gautam Bhatia, a New Delhi based architect and writer.

"So a three-story structure will support a five-story structure," Bhatia said. "The result will be a building that is structurally dangerous, with rooms leaning precariously in mid-air."

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Olesen reported from Beijing and George from New Delhi. Associated Press writer Elaine Kurtenbach in Shanghai and researchers Xi Yue in Beijing and Ji Chen in Shanghai contributed to this report.