The U.S. Embassy in Chad has been shuttered since Tuesday and will remain closed through Friday, Sept. 11, due to a credible terrorist threat from the Boko Haram terrorist group, a military source tells Fox News.

"For security and safety reasons U.S. embassy staff are prohibited from visiting public open-air markets; public places of worship; public events not held at U.S. government facilities," read a warning posted to the the embassy's website.

Boko Haram is active in primarily in northeast Nigeria, but has a presence in neighboring Cameroon, Niger and Chad.

Boko Haram is best known for kidnapping over 200 girls in northern Nigeria sparking international outrage and the #bringbackourgirls campaign which included photos of celebrities including the First Lady.

This spring, Boko Haram pledged allegiance to the Islamic State.

A look at U.S. Embassy N'Djamena, Chad website confirms the embassy has been closed since Tuesday and will be closed through 9-11.

This is the second security threat in the past two days on the African continent.

The United States Diplomatic Mission to South Africa issued a security message warning U.S citizens that it had "received information that extremists may be targeting US interests in South Africa."

The State Department would not immediately reveal how many embassies worldwide had issued security warnings this week in the days leading up to September 11 when contacted by Fox News.

An official told Fox News that security messages are issued by embassies to inform U.S. citizens living in the country to threats that could impact them.

The U.S. has closed its embassies in Syria, Libya and Yemen in the past two years.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews