(CNN) The death toll in Sunday's flash flooding in a national park in Kenya has increased to six and rescue teams are still looking for one tourist, Kenya's Wildlife Service said on Monday.

The tour group of seven people -- five Kenyans, a local tourist guide and a "non-resident foreigner" -- had been caught in the flash flood Sunday in Hell's Gate National Park.

"Six bodies of the flash flood victims have been recovered, leaving one tourist missing. The search and rescue operation continues as we reach out to next of kin to share details of sad incident and plan together next course of action," KWS on its official Twitter page.

Search and rescue teams had initially recovered two bodies on Sunday but four more were found as efforts continued throughout the night, KWS said.

A helicopter was dispatched from the capital Nairobi, which is about 100 kilometers (62 miles) southeast of the park, to help with search efforts on Sunday

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