Jakarta. Four construction workers were killed and three others injured after allegedly inhaling toxic gas inside a water storage tank at a high-rise project in South Jakarta, authorities said.

The incident occurred at a construction site on Jalan TB Simatupang in Tanjung Barat, Jagakarsa. The victims who died were identified as Yana Nugraha, 33, from Subang; Mawi, 63, from Cianjur; Tatang Sonjaya, 64, from Subang; and Muhammad Fauzi, 20, from Bandung, all in West Java.

Police said the accident began when the four workers were instructed by a supervisor to drain a clean water storage tank located in the building’s basement. Upon opening the tank, which is about three meters deep, the workers suddenly collapsed and fell inside.

Three other workers who attempted to rescue them also fell into the tank after entering without proper safety equipment.

The incident triggered panic among other workers at the site, who rushed to evacuate the victims from the confined space. All seven were transported to Pasar Rebo Regional General Hospital for initial treatment.

Four of the workers were pronounced dead, while the three survivors suffered breathing difficulties and are currently receiving intensive care at Fatmawati Hospital.

The bodies of the deceased were later transferred to the Kramat Jati Police Hospital morgue for further examination as part of the investigation.

Authorities suspect the victims were exposed to toxic gas inside the tank, a theory supported by witness accounts from the scene.

Muhammad Akip, a nearby resident who attempted to assist, said he experienced extreme heat and shortness of breath when approaching the tank.

“When I got closer, it felt hot and I had difficulty breathing,” he said.

The case is being investigated by South Jakarta Metro Police and Jagakarsa Police precinct officers, who have processed the scene and questioned at least three witnesses to determine the exact cause of the incident.

Police urged construction companies to strictly adhere to occupational safety standards, particularly when working in confined spaces, to prevent similar tragedies.