At least 21 people were killed and 15 injured Tuesday when a bus carrying students to take their college entrance exams plunged into a lake in southwest China, according to reports.

The bus was seen in surveillance video plowing across several lanes through a guardrail and veering into Hongshan Lake in Guizhou province about noon local time, emergency management officials said, Agence France-Presse reported.

The Anshun city government said the bus was hauled out of the lake after the injured were rushed to local hospitals.

The vehicle included high school students who were to take the grueling “gaokao” exams, state broadcaster CCTV reported. It was not immediately clear how many students were killed.

Social media users expressed their condolences on the country’s microblogging site Weibo.

“I hope the death toll will not rise anymore. 2020 has truly been full of disasters and difficulties,” one user said.

Officials said more than 200 people helped with rescue efforts, including 55 professional divers, AFP reported.

Authorities pledged an investigation into the cause of the tragedy.

Across China on Tuesday, some 10.7 million students began taking the college entrance exams in 400,000 rooms, according to the People’s Daily.

But in addition to the bus accident, torrential rain also prevented about 2,000 students from taking tests on Chinese language and math in the eastern Anhui Province, the Xinhua news agency reported.

With Post wires