About 50 workers were inside the factory south of Phnom Penh, the capital, when the ceiling caved in, said police officer Khem Pannara. He said heavy iron equipment stored on the floor above appeared to have caused the collapse.
Two bodies were pulled from the wreckage and seven people were injured, he said. Rescuers combed through rubble for several hours and after clearing the site said that nobody else was trapped inside.
"We were working normally and suddenly several pieces of brick and iron started falling on us," the 25-year-old said.
An initial investigation showed the ceiling that collapsed was poorly built and lacked the proper building materials to support heavy weight, said Ou Sam Oun, governor of Kampong Speu province, where the factory was located.
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Chea Muny, chief of a trade union for factory workers, identified the factory as a Taiwanese-owned operation called Wing Star that produces sneakers for Asics, a Japanese sportswear label. He said shoes made at the factory were imported to the United States and Europe.
The garment industry is Cambodia's biggest export earner, employing about 500,000 people in more than 500 garment and shoe factories. In 2012, the southeast Asian country shipped more than USD 4 billion worth of products to the United States and Europe.
The accident comes about three weeks after a building collapse in Bangladesh killed 1,127 people in the global garment industry's deadliest disaster.
Last month, the UN's labor office released a report that called for "urgent attention" to worker safety violations in the Cambodian garment and footwear industry.