Twenty-seven people were killed in a bus crash in southwest China on Sunday, police said, in the country's deadliest road accident so far this year.

The crash took place on a highway in rural Guizhou province when the vehicle carrying 47 people in total "flipped onto its side", police said in a statement published on social media.

The remaining 20 people were being treated for injuries and emergency responders were dispatched to the scene, police said, without providing any more details.

The accident happened in Qiannan prefecture -- a poor, remote and mountainous part of Guizhou, home to several ethnic minorities.

In June, a driver was killed after a high-speed train derailed in Guizhou province.

And in March a Chinese passenger jet crash killed all 132 people on board, marking the deadliest aviation accident to take place in China for decades.