Gunmen kidnapped four Thai nationals as they travelled to a farm in Nigeria's Rivers state, the local government said on Saturday.
State commissioner for agriculture Emmanuel Chindah said by telephone that the gunmen stopped their vehicle on its way to Omida farms in the Buguma area of the riverine state on Friday. They kidnapped the Thais and their two Nigerian colleagues.
"The two Nigerians were immediately released. But in that process one panicked and jumped into the water and drowned," he said.
Nigeria is one of the world's worst countries for kidnapping, and levels are high in Rivers state, where petro-dollars flowing from Africa's biggest oil industry have long been a draw for criminal gangs.
The gangs make many millions of dollars a year from extorting ransoms.