Pirates have stormed an oil supply vessel off the coast of Nigeria and taken two Americans hostage.
The London-based security firm AKE says pirates attacked a U.S.-flagged ship named C-Retriever on Wednesday and kidnapped the ship's captain and chief engineer.
There was no immediate word on the identities of the two Americans, and no immediate claim of responsibility.
The International Maritime Bureau has warned of increasing pirate activity in the Gulf of Guinea off West Africa. The bureau says prior to Thursday, there have been 30 reported incidents near Nigeria this year, including two hijackings.