TEHRAN, Iran (AP) — Iran's official IRNA news agency says three seamen have died from an unspecified toxic substance that poisoned all 11 crew members of an Iranian cargo ship on the Caspian Sea.

Friday's report says the crew of the vessel, Nazmehr, was transferred to a hospital in Baku, Azerbaijan, but that the three seamen died before they reached the hospital. IRNA says the case is under investigation.

The ship was carrying grain from Kazakhstan to Azerbaijan.

The ship's captain stayed aboard and was given medical assistance, according to Azerbaijan's health care ministry.

Ministry spokesman Parviz Abubekirov said preliminary information indicated that the crew had been poisoned by chemicals used to protect grain.

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