TAIPEI (Taiwan News) — The unordered parcel causing health problems for people who opened it in South Korea was sent from the Chinese city of Shenzhen, Vice Premier Cheng Wen-tsan (鄭文燦) said Saturday (July 22).

Employees at a welfare center in Ulsan suffered from dizziness and breathing difficulties after opening the package Thursday (July 20). Though it was marked as having been sent from Taiwan, an investigation showed that it moved by ship from Shenzhen to Taiwan as a parcel before being sent as air mail by Chunghwa Post from Taiwan to South Korea, Radio Taiwan International (RTI) reported.

Cheng said the investigation was still continuing, and the authorities would see where procedures needed to be strengthened. According to the Criminal Investigation Bureau (CIB), the parcel was handled in transit at a special Chunghwa Post sorting center and never entered Taiwan.

As similar unordered packages showed up in other South Korean cities, Chunghwa Post said it had stopped shipping such parcels to South Korea, per UDN. Police in the northeast Asian country advised residents not to open packages wrapped in yellow or black plastic from Taiwan for the time being.

If a guilty party is found, they could be fined NT$150,000 (US$4,800), per CNA. According to Chunghwa Post, sending items from China to other countries by the transshipment method via Taiwan is faster and cheaper than sending them from China directly to the country of destination.