SHANGHAI — For the eighth time this year, a worker has apparently committed suicide at a factory in China operated by Foxconn Technology, the world’s biggest contract electronics maker and a major supplier to Apple, Dell, Hewlett-Packard and other companies.

The worker, a 21-year-old man named Nan Gang, jumped from a four-story factory after leaving work at 4 a.m. Friday, Xinhua, the official Chinese news agency, reported. Two other Foxconn workers have survived suicide attempts, but have suffered serious injuries.

No one has been able to explain what is happening at Foxconn. But the events are again raising questions about the harsh regimens used by Chinese factories to produce a growing share of the world’s goods.

Labor rights groups have called some of the deaths suspicious and have asked for an independent investigation of the two Foxconn factory sites, which together employ about 420,000 workers in Shenzhen, China.