The Office of the Work Safety Commission under China's State Council has decided that it will oversee the investigation into a passenger bus accident in southwest China's Yunnan Province, which left seven dead and 12 injured, the Ministry of Emergency Management said on Thursday.

The accident occurred Thursday in Yuanyang County, when a passenger bus overturned. The Ministry of Emergency Management, together with the Ministry of Public Security and the Ministry of Transport, dispatched a joint working group to the scene to guide rescue and response efforts.

The office has required Yunnan authorities to elevate the investigation level, demanding a swift determination of the cause, and strict accountability in accordance with the law.

The measures aim to draw lessons from the accident and prevent similar incidents from recurring in the future.