The Tiantou Elementary School was buried Thursday when the hillside collapsed in Zhenhe, a village in Yunnan province, the Yiliang County government said on its website.
All 18 students who were buried in the school were confirmed dead, the government said. The official Xinhua News Agency said the body of a 19th victim was found Friday. It gave no details, but the county government said earlier that a person was missing from a house that had collapsed.
The government also said that a person injured in the landslide was hospitalized.
The landslide dammed a river, causing its water to pool 15 meters (45 feet) across and 7 meters (21 feet) deep around the buried area, hampering rescue efforts and forcing the evacuation of 800 other people, the government said. Rescue teams removed the blockage and the water was subsiding.
While officials have yet to give a cause for the landslide, that part of Yunnan province has been lashed by rain and is prone to earthquakes. A series of quakes last month left 81 people dead and devastated parts of Yiliang county, which are still recovering.
Thursday was a holiday across China, but the students who were killed had been attending school to make up for days missed after the quake, Yiliang officials said. Xinhua said their school was damaged in the quake and they were sent to Tiantou temporarily.