Updated

The situation in Liberia went from bad to worse Monday as mortar duels between government and rebel forces killed more than 90 people in the capital, Monrovia (search), with one shell striking the commissary on the grounds of the U.S. Embassy.

At least three people were confirmed injured in the commissary attack; aid workers told Fox News' Jennifer Eccleston, holed up in the embassy grounds with other journalists, that some people had been killed.

Far more devastating was a direct hit on the diplomatic residence compound across the street, in which 25 people were killed. An estimated 10,000 refugees had taken shelter from the fighting in the compound.

Reuters reported early Tuesday that Liberia's Defence Minister Daniel Chea said more than 600 civilians have been killed in Monrovia over the past few days.

Enraged Liberians lined up at least 18 bloodied, mangled bodies from the compound in the street outside the embassy. Some shouted, "We are going to die for nothing," as two embassy guards watched from behind bulletproof glass.

Helicopters delivering a detachment of 41 Marines from the Fleet Anti-Terrorism Security (searchTeam, clad in green camouflage, body armor and helmets, loaded up with about 25 or 30 fleeing Western aid workers and journalists before taking off again for the safety of Freetown, capital of neighboring Sierra Leone (search).

"We're concerned about our people," President Bush told a press conference in Crawford, Texas.

"We are strongly condemning the rebel group ... for their continued reckless and indiscriminate shelling of Monrovia," said State Department spokesman Philip T. Reeker.

The Pentagon also announced that some 4,500 more American sailors and Marines have been ordered to position themselves closer to Liberia to be ready for possible duty in the embattled West African nation.

The mortar incident came as Liberian frustration grew at an apparent diplomatic Catch-22.

Bush has said U.S. peacekeepers won't land in Liberia until warlord-turned-President Charles Taylor (search) leaves. Taylor has pledged to resign and accept an offer of asylum in Nigeria - but only after peacekeepers arrive.

Aid organizations were evacuating staff from the area; some were even leaving the country. The embassy had already been downsized considerably and strong warnings had been issued to Americans to leave.

One of those being evacuated to Freetown, aid worker Eleanor Monbiot of World Vision (search), said that her organization had to stop food distribution on Friday because workers were hunkered in a compound.

"The situation is very dire," Monbiot told Fox News, adding that the looting is particularly rampant in the center of town. "In fact, this is the worst attack we've seen on the city in recent years."

Major Bill Bigelow, a spokesman for U.S. European Command in Stuttgart, Germany, said an American reporter was injured outside the embassy and two local security guards were hit. Tom Masland, the African regional editor for Newsweek, had three pieces of shrapnel in his arm.

Bush on Monday said during a news conference on his Texas ranch with Italian Premier Silvio Berlusconi that he would work with the United Nations to help restore a cease-fire.

But he indicated that he hadn't decided on the size of the U.S. peacekeeping force.

"We continue to monitor the situation very closely," Bush said.

Reeker stressed that the United States is waiting for the Economic Community of West African States (search) to take the lead in Liberia. West African nations are planning to send more than 1,500 soldiers to enforce the often-violated June 17 cease-fire.

"Clearly, we want to see the ECOWAS troops deploy, as they have discussed," Reeker said. "We want to do what we can to support that. The president will make appropriate decisions at the time."

It was unclear whether Taylor's government troops even had mortars. The hits on the embassy may be indiscriminate fire, since the rebels have said they did not want to target the embassy because of the Americans inside and the tens of thousands of refugees in the area.

Taylor over the weekend ordering his militiamen to fight in the streets and go house-to-house to quash the "evil forces" of rebels. He said he would not abandon his people and would only go into exile after peacekeepers arrived in Monrovia, Taylor's only remaining stronghold.

Meanwhile, military officials at the Pentagon told Fox News Monday that with the worsening security conditions in Monrovia, they were "waiting" to hear that the Marine expeditionary unit - under the command of U.S. Central Command's Horn of Africa anti-terror task force - had been ordered to the war-ravaged West African country.

Speaking on condition of anonymity, the officials said that though they had no information that the 26th Marine Expeditionary Unit (search) had yet been ordered to West Africa, they did know that the amphibious assault ship that serves as the Marines' floating base, the USS Iwo Jima, was in the Red Sea and "on the move."

Even if the ship were heading toward West Africa, the trip could still take a week and a half. But officials said they fully expected to see orders moving the Marines to Liberia in short order.

The State Department has called for an immediate cease-fire by all parties and a focus on continuing peace talks in Ghana aimed at setting up a unity government to oversee fresh elections.

The department last issued a travel warning June 6 for Americans in Liberia, saying "periodic inflammatory statements in the local media regarding U.S. policies and presence in Liberia could also incite violence against American interests."

Liberians are weary after 14 years of bloody turmoil. Many said they would not believe stability was possible until U.S. peacekeepers landed in the country.

"We hold George Bush responsible for this mess," shouted a member of Taylor's elite Anti-Terrorist Unit.

Gen. Abdulsalami Abubakar (search), the former Nigerian military ruler mediating peace negotiations in Ghana, also appealed for an end to the fighting.

Reeker attributed the attacks to the rebel movement Liberians United for Reconciliation and Democracy (search).

"There is a cease-fire that needs to be upheld, and all of the parties in Liberia have responsibilities to see that that happens, in the interest of the future of Liberia, as well as the immediate safety of the Liberian people in Monrovia and those that are there to help them," Reeker said.

Officials for the LURD insisted they were only trying to pressure Taylor to step down.

"We're not trying to do a military takeover," LURD delegate Joe Wylie said in Ghana. "But we can help to speed things up. Since Taylor signed the cease-fire, he is running his mouth and amending his promises. We want to apply a little pressure on him. We want him to leave now."

Taylor launched Liberia's last civil war in 1989, emerging in 1996 as the country's strongest warlord. He was elected president the following year, and now faces rebels who include former rivals from the earlier war.

A U.N.-backed tribunal has indicted him on war crimes for supporting Sierra Leone's notoriously brutal rebels.

Fox News' Jennifer Eccleston, Ian McCaleb and Teri Schultz and The Associated Press contributed to this report.