Twenty-seven people were killed when their bus crashed in southwest China, en route to a COVID-19 quarantine facility. It is the country's deadliest road accident in 2022.

Based on the police statement, the bus overturned on a section of a highway leading from Guiyang to Libo, a county just south of Sandu, and was carrying 47 people. On Sunday, an official from the Sandu county government's publicity department told Reuters that all 20 injured were being treated in hospitals.

The accident happened at about 2:40 am on Sunday, according to the Guizhou government, and the car had been "transporting people linked to the epidemic to quarantine" from Guiyang, the provincial capital.

Despite testing negative for COVID-19, some housing compound residents were forced to leave their homes and were bused to crude quarantine facilities in neighboring provinces in the middle of the night during a two-month lockdown in the megacity of Shanghai this spring.

Road accidents continue to be relatively common in China, where inconsistent enforcement and lax safety standards have resulted in a slew of fatalities over the years.

Unverified reports and photos of the bus circulating on Chinese social media on Sunday afternoon sparked a renewed outpouring of rage at China's strict COVID policies and the authorities' initial lack of transparency.

It was unclear if the passengers had the COVID-19 virus, were in close contact with the sick or lived in the same building.

In the last two days, there have been more than 900 new illnesses in Guizhou, and Guiyang, which has a population of six million, was placed under lockdown earlier in September.

Photos began circulating widely on social media on Sunday of a gold-colored passenger bus being towed by a truck with its top completely crumpled.

Local authorities are under pressure to keep outbreaks under control, particularly as the party congress approaches.

Guizhou recorded 712 new confirmed cases on Saturday, accounting for roughly 70% of all new cases in China, up from 154 cases the day before, according to data from China's national health commission released on Sunday.

The Communist Party chief of Guizhou and the provincial governor "rushed" to Qiannan prefecture to direct emergency response work, according to the local government, adding that the officials "expressed heartfelt condolences to the victims."

"It is necessary to learn from the accident, investigate quarantine and transportation of epidemic-linked personnel, and uncover hidden dangers in traffic safety... resolutely reduce the occurrence of major accidents," the statement said.