Four U.S. soldiers and five civilians in two boats were taken captive by Iranians, blindfolded and interrogated before being released, U.S. Central Command (search) said Monday. Two of the civilians were still being held.

Four soldiers from the Army's 1092nd Engineer Company, a civilian Army contractor, two civilian captains and two boat drivers were sailing up the Shatt al Arab waterway in the al Faw peninsula (search) Sunday to pick up Iraqi South Oil Co. personnel when they were taken by force by Iranians, a spokesman, Cmdr. Dan Gage, said from Central Command headquarters in Tampa, Fla.

The nationalities of the civilians were not available.

The boats were to take the oil company personnel to the Mini al Bakr platform to conduct a survey of the oil platform when the Iranians blindfolded them and took them to a building where they were interrogated throughout Sunday night, Gage said.

On Monday, the Iranians took the group back to their boats and released all of them except the two drivers, Gage said.

Chinook helicopter (search) located them near the waterway Monday, Gage said. U.S. Navy crew members drove the boats to Kuwait.

Initial medical examinations indicate there were no injuries or signs of physical abuse, Gage said.

The group may have moved into Iranian territorial waters, he said. The Mini al Bakr platform is very close to Iran's declared international water boundaries.