BANGKOK (Reuters) - At least eight people, six of them foreign tourists and including a 10-year-old German boy, drowned when a flash flood trapped them in a cave in southern Thailand, police said on Sunday.

Another foreigner was believed to have been in the party visiting the Nam Talu cave in Khao Sok national park and rescuers were still searching the area, Police Lieutenant Colonel Pichan Kalayasiri said.

"We have found eight bodies so far, including six foreigners and two Thais," he said by telephone from Surat Thani province, where the forested park draws trekkers and bird watchers.

"The dead included a 10-year-old German boy, but officials still cannot tell the nationalities of the three women and two men," he said.

The two Thais were a tourist guide and a boatman who took the party to the 500 metre (1,640 ft) deep Nam Talu cave on the Rachaprpa reservoir, which is home to bats.