A bus carrying 19 secondary vocational schoool students in southwest China's Sichuan Province slipped off a high slope Monday, leaving four seriously injured, local authorities said. The bus turned over and fell off a 10-meter-plus slope at about 1:30 a.m. in Zhongjiang County, Deyang City, when it was returning from a tour, the county government said. The 19-seat bus had 21 on board, including a teacher and a driver. The four are under emergency treatment and the rest who suffered slight injuries are also being treated, doctors at the county people's hospital said.