The State Department, responding to the terrorist attacks in Kenya, said Friday that Americans there should remain vigilant, particularly in public places frequented by foreigners.

In a public announcement, the department said Thursday's attacks "have highlighted the continuing threat posed by terrorism in East Africa and the capacity of terrorist groups to carry out attacks."

In the incidents Thursday, 11 persons were killed in a car bombing in Mombasa. Also, there was an unsuccessful attempt to shoot down an Israeli charter plane.

"U.S. citizens should be aware of the risks of indiscriminate attacks on civilian targets in public places, including tourist sites and other sites where Westerners are known to congregate," the announcement said.

American citizens in Kenya, it added, should remain vigilant in hotels and shopping malls, and should also avoid demonstrations and large crowds.