TAIYUAN -- Four firefighters were engulfed by a forest fire in North China's Shanxi province and were found dead on Monday, local authorities said Tuesday.

The fire broke out around noon on Monday in Wenjiazhuang Village of Taigu County, the county's publicity office said.

The fire was put out late Monday. An initial investigation showed that it was caused by a villager, surnamed Cheng, who burned paper money when visiting relatives' tombs before Tomb Sweeping Day.

Cheng was taken into police custody.

Tomb Sweeping Day, which falls on April 4 this year, is a time for Chinese people to pay respects to deceased family members. Traditionally, the tributes involve burning incense and paper money, occasionally causing fires in the wild.