Six workers died and three others were injured in a cave-in accident at a construction site in south China's Guangdong Province on Sunday, local government said.

The cave-in occurred at about 10:20 a.m when nine people were constructing an underground parking lot in the city of Xinyi, and all of them had been dug out by 5:30 p.m., said a spokesman with the city.

Six were dead despite medical efforts, and the injuries of the other three were not life-threatening, the spokesman said.

The cause of the accident is under investigation.