(WASHINGTON) — Two U.S. officials tell ABC News that Americans are among the hostages held following the attack on a BP joint venture natural gas field in Algeria.

One of those officials, a senior intelligence official, says that currently it appears three U.S. citizens are being held. However, this official cautions that the numbers can change as can the overall number of hostages.

The FBI said it is monitoring the situation.

In a briefing, State Department Spokesperson Victoria Nuland said, “U.S. citizens are among the hostages. In order to protect their safety I’m not going to get into numbers, I’m not going to get into names, I’m not going to get into any further details as we continue to work on this situation with Algerian authorities and also their employers.”

Nuland said the U.S. “condemns in strongest terms the terrorist attack on BP facilities. We are obviously closely monitoring the situation and in close contact with the government of Algiers and BP’s security.”

Secretary Clinton has spoken to the U.S. Ambassador in Algeria and is speaking with Algerian Prime Minister Abdelmalek  Sellal.

The Embassy has issued an emergency message to American citizens in Algeria in the context of this incident.

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