File photo of Foreign Ministry Spokeswoman Hua Chunying [Photo: fmprc.gov.cn]

Six Chinese nationals were injured in Laos on Wednesday night, after unknown gunmen opened fire on a bus.

The Chinese embassy says 25 passengers and three drivers were on the bus, traveling from Yunnan province to Laos.

Foreign Ministry Spokeswoman Hua Chunying said Beijing has demanded a thorough investigation by authorities in Laos.

"The consular department of China's Foreign Ministry, and the Chinese embassy and consulate in Laos, made representations to Laos right after the incident took place, and requested Laos to dispatch military police to spare no effort to rescue the injured and properly relocate other passengers; moreover, to take concrete and targeted actions to reinforce the safety and protection of local Chinese nationals. At the moment, the injured have been sent to hospital for first aid, and other passengers have received proper relocation."

The incident took place in the Kasi area in northern Laos.

Two of the injured were shot multiple times and are in serious condition.

The embassy has advised Chinese travelers to exercise caution.