Foxconn Technology Group, the main manufacturing contractor for Apple’s iPad 2 and iPhone 4, witnessed a large explosion in its Chengdu plant on May 20 7 p.m. local time, killing 2 and injuring at least 16, and possibly delaying the already-scarce iPad supply.

The cause of the explosion, which resulted in fire later, is unknown at the moment and Foxconn said the case is under investigation by local police. However, preliminary investigations have revealed that accumulation of aluminum dust in the ventilation pipe of the central air conditioning unit triggered a spark, leading to the fire and explosion.

“Production has been suspended at the site of our employees until the completion of the investigation,” said Qian Ding, the spokeperson of Foxconn. “The safety of our employees is our highest priority and we will do whatever is required to determine and address the cause of this tragic accident,” added Qian Ding.

The explosion is expected to affect the supply of iPad 2 by a few weeks. Foxconn was already under immense pressure to meet the demand for iPad 2 and iPhone 4 as Japan’s earthquakes have delayed supply shipments.

Moreover, Foxconn has its own labor problems. The company is under international scrutiny because at least 13 of its employees have committed suicide and rights groups claim the suicide are triggered by high-level of stress. Although the company’s supporters argue that the suicide rate is lower than the national suicide rate in China, critics say the workers are under harsh condition with long hours and low pay.

These days, people have to wait in long lines before the Apple stores open every morning to have any chance of purchasing an iPad 2. And even then, not everyone gets to pick them up.

It is uncertain whether Apple and Foxconn can recover from this unforeseen event quickly, but one thing is certain – it is definitely not a good way to kick off Apple’s celebration of 10th Anniversary of its retail stores, which starts tomorrow.

Neither Foxconn nor Apple responded to a request for comment regarding iPad production.

Watch the video below on Foxconn explosion.