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Soldiers guard a checkpoint in Algeria just outside a desert gas plant that is still under siege.

Authorities block access as the army carries out a "final assault" on al Qaeda-linked gunmen holed up in the plant. Algerian forces reportedly killed 11 Islamists after they took the lives of seven foreign hostages.

Survivors are treated in Algiers. The number and fate of victims has yet to be confirmed.

One man recounts the ordeal.

(SOUNDBITE) (Arabic) UNIDENTIFIED MAN, SAYING:

"They attacked us at 5:30 in the morning. When we heard the shooting we all went out to see what was happening, so then we ran and hid. Some of us died and some hid in bedrooms. Some of the terrorists followed us to the bedrooms."

In London, Foreign Secretary William Hague says the crisis is not over.

SOUNDBITE (English) BRITISH FOREIGN MINISTER WILLIAM HAGUE, SAYING:

"As of now there are fewer than 10 British nationals at risk or unaccounted for, but that of course means that we must continue to prepare ourselves for bad news."

Estimates on the number of hostages killed range from 12 to 30. Many foreigners are still unaccounted for.