As the United States rushed medical supplies and investigators to Africa, President Clinton pledged on Friday to bring the terrorists who bombed U.S. embassies in two countries to justice "no matter what or how long it takes."

The "apparently coordinated" attacks in Kenya and Tanzania marked an unprecedented simultaneous assault on U.S. sites, said Thomas Pickering, the State Department's undersecretary for political affairs.At least 80 people, including eight Americans, died. More than 1,700 others were injured. U.S. officials described the bombings as coordinated attacks by unknown, sophisticated terrorists.

Authorities in Kenya, where most of the casualties occurred, said hundreds remain unaccounted for. It may take days, they said, to remove all the bodies believed trapped in the debris. More than 10 hours after the bombing there, U.S. officials said six Americans were still missing. No Americans died in the Tanzania blast, but three Tanzanian guards were killed as were two embassy employees.

Security measures were heightened at American embassies throughout Africa and around the world. Flags at official buildings were lowered to half staff.

Questioned about the vulnerability of the two U.S. installations that were attacked, Pickering said: "Bomb-proof is a relative term. Tell me what size bomb, and I'll tell you what the proof is.

"We have a set of standards which we believe deals with most of the difficulties, if not all of the difficulties, that we expect to face, and it is clear that these two buildings did not meet our current standards," he said.

Clinton was awakened at 5:30 a.m. by National Security Adviser Sandy Berger with news of the bombings. Secretary of State Madeleine Albright cut off a private visit to Italy to return home for an emergency meeting with a State Department task force set up to deal with the situation. Attorney General Janet Reno canceled a Denver trip to stay in Washington.

"These acts of terrorist violence are abhorrent, they are inhuman," Clinton said at the White House. "We will use all the means at our disposal to bring those responsible to justice, no matter what or how long it takes."

In Rome, Albright said, "The United States government is currently mobilizing all necessary capabilities both inside and outside the region to deal with all aspects of this human catastrophe."

She called the bombings "dastardly and cowardly acts."

No group claimed responsibility, and officials declined to speculate. They did say, however, that the bombings were clearly terrorist attacks. Among those dispatched to Africa were anti-terrorism teams, including FBI agents and U.S. Marines.

"This appears to have been a very well-coordinated, very well- planned attack - clearly not the work of amateurs," National Security Council spokesman P.J. Crowley said. "We have already launched our investigation,"

He said the United States was in the process of identifying the dead and notifying the next of kin.

Aircraft took off from the United States, Europe and elsewhere in Africa bearing medical supplies and other equipment, along with replacement personnel for the two embassies.

"There are folks out there who are trapped as we speak; you are their best chance," Fairfax County fire chief Glenn Gaines told task force members as they assembled for deployment.

In a hangar-like room they stowed back packs and yellow helmets into a truck for the trip to Andrews Air Force Base and a 16-hour flight to Nairobi, Kenya. A team member explained that the red back backs contained gear for immediate needs while the yellow packs held changes of clothing to last a week.

The team, which assisted in the aftermath of the Oklahoma City bombing, is made up of experts with listening devices, fiber-optic cameras, medical units, dog teams and special engineering teams that go into rubble in search of victims.

A U.S. official with access to sensitive material said the administration has received numerous threats worldwide to American interests. He said the operations Friday may have taken several months to plan, given the coordination involved.

Islamic Jihad, the strongly anti-West and anti-Israel group that often receives its direction from Iran, has vowed to take revenge against the United States, blaming it for the arrest of a number of its members, including three detained recently in Albania.

Asked whether the Islamic Jihad was under suspicion, Pickering said 30,000 threats are received by the State Department each year. He added that he could not talk about investigations.

At the Capitol, reaction was quick and full of condemnation.

"The United States of America takes very seriously assaults on its citizens," House Speaker Newt Gingrich said. "We should do everything we can to track down the people who've done this and to make them pay to the fullest extent."