TAIPEI (Taiwan News) — A chemical explosion at a National Chung-Shan Institute of Science and Technology (NCSIST, 中科院) missile facility in Pingtung County injured four people on Thursday (Aug. 3).

The fire occurred around 10 a.m. when staff at the institute's Jiupeng Base were destroying excess ammunition, the Liberty Times reported. Of the four injured, the 51-year-old supervisor suffered second to third-degree burns on 95% of his body, and was still in critical condition Thursday evening, per CNA.

The victims, between the ages of 40 and 51, were first transferred to three hospitals in the county, but they were later moved to a military hospital in Kaohsiung City's Zuoying District.

A special working group is to investigate the cause of the incident and determine responsibility. A spokesperson at the facility said all four injured had between five and 10 years of experience with the work they were doing Thursday, while similar procedures occurred every week.

The Ministry of National Defense (MND) reported the incident to the Presidential Office, with President Tsai Ing-wen (蔡英文) expressing concern for the staff and asking for a quick investigation.

NCSIST is a state-owned corporation known for researching, developing, and producing weapons systems, including missiles and unmanned aerial vehicles.