MOGADISHU, Somalia — A U.S. airstrike hit targets in southern Somalia where Islamic militants were believed to be sheltering suspects in the 1998 bombings of two U.S. embassies, Somali officials and witnesses said today. Many people were reported killed.

Monday's attack was the first overt military action by the U.S. in Somalia since the 1990s and the legacy of a botched intervention — known as "Black Hawk Down" — that left 18 U.S. servicemen dead.

Helicopter gunships launched new attacks today near the scene of the U.S. airstrike, although it was not clear if they were American or Ethiopian aircraft, and it was not known if there were any casualties.

Two helicopters "fired several rockets toward the road that leads to the Kenyan border," said Ali Seed Yusuf, a resident of the town of Afmadow in southern Somalia.

The aircraft carrier USS Dwight D. Eisenhower arrived off Somalia's coast and launched intelligence-gathering missions over Somalia, the military said. Three other U.S. warships are conducting anti-terror operations off the Somali coast.

U.S. warships have been seeking to capture al-Qaida members thought to be fleeing Somalia after Ethiopia invaded Dec. 24 in support of the government and drove the Islamic militia out of the capital and toward the Kenyan border.

The White House would not confirm the attack, nor would the Pentagon.

But a U.S. government official said at least one AC-130 gunship was used. The official spoke on condition of anonymity because of the operation's sensitivity.

AC-130 gunships have elaborate sensors that can go after targets day or night. They are operated by the Special Operations Command and have been used heavily against the Taliban in Afghanistan.

The airstrike occurred Monday evening after the suspects were seen hiding on a remote island on the southern tip of Somalia, close to the Kenyan border, Somali officials said. The island and a site 155 miles north were hit.

The main target was Fazul Abdullah Mohammed, who allegedly planned the 1998 attacks on the U.S. embassies in Nairobi and Dar es Salaam, Tanzania, that killed 225 people.

He is also suspected of planning the car bombing of a beach resort in Kenya and the near simultaneous attempt to shoot down an Israeli airliner in 2002. Ten Kenyans and three Israelis were killed in the blast at the hotel, 12 miles north of Mombasa. The missiles missed the airliner.

Fazul, 32, joined al-Qaida in Afghanistan and trained there with Osama bin Laden, according to the transcript of an FBI interrogation of a known associate. He came to Kenya in the mid-1990s, married a local woman, became a citizen and started teaching at a religious school near Lamu, just 60 miles south of Ras Kamboni, Somalia, where one of the airstrikes took place Monday.