The rapid string of strikes, all within less than half an hour, set off thunderous booms that rattled windows, sent heavy, acrid-smelling plumes of smoke over the city, including from an area close to Gadhafi's sprawling Bab al-Aziziya compound.
Government spokesman Moussa Ibrahim said at least three people were killed and dozens wounded in NATO strikes that targeted what he described as buildings used by volunteer units of the Libyan army.
NATO said in a statement that a number of the strikes hit a vehicle storage facility adjacent to Bab al-Aziziya that has been used in supplying regime forces "conducting attacks on civilians." It was not immediately clear if the facility was the only target hit in the barrage. Bab al-Aziziya, which includes a number of military facilities, has been pounded repeatedly by NATO strikes.
The military aircraft whooshed low over the city during the night, the strikes coming in series of three loud booms, a pause of minutes punctuated by the hissing sound of low-flying jets, then more shaking, shuddering strikes, shaking windows miles away from Bab al-Aziziya. The sound of other more distant explosions could also be heard.
Pro-Gadhafi loyalists beeped their car horns and fired guns, shouting their support for the Libyan leader. Armed men sprayed the night sky with gunfire in response. Men screamed and shouted outside the hotel where journalists were staying, declaring their loyalty to Gadhafi.
Observers described the bombing as the heaviest attack on the Libyan capital since NATO began its air campaign on March 19 after the passage of a U.N. Security Council resolution to protect civilians after Gadhafi responded to the public uprising against his rule by unleashing his military and his militias.
In one room of the Tripoli Central Hospital, the bodies of three mangled men in their twenties lay on stretchers, their clothing ripped and their faces partially blown away and dusty. A nurse, Ahmad Shara, told reporters taken on a government-escorted visit to the facility soon after the strikes that the men were standing outside their homes when they were killed, presumably by shrapnel.
One man who identified himself as a relative walked into the room where the bodies lay. He halted at their sight, turned around and loudly slapped his hands on a wall as he cried out in shock. Around 10 other men and women lay on stretchers. They appeared moderately to lightly wounded.
"We thought it was the day of judgment," said Fathallah Salem, a 45-year-old contractor who rushed his 75-year-old mother to the hospital after she suffered shock. The wide-eyed man described how his home trembled, his mother fainted and how the younger of his seven children cried as they heard the rolling explosions.
"You were in the hotel and you were terrified by the shaking - imagine what it was like for the people who live in slums!" Salem said, as he interrupted a government spokesman to speak to a crowd of foreign reporters at the hospital.
"Honestly, we used to have problems (with the regime)," he said in Arabic. "But today we are all Moammar Gadhafi."
NATO, which said in its statement that it took care to "minimize the risk of collateral damage to the fullest extent possible," has been escalating and widening the scope of its strikes over the past weeks, hiking the pressure on Gadhafi, while the alliance's members have built closer ties with the rebel movement that has control of the eastern half of Libya. On Monday, the highest-ranking U.S. diplomat in the Middle East, Jeffrey Feltman, was in the de facto rebel capital of Benghazi in a show of support.
Despite NATO bombing runs, the rebels have not been able to break Gadhafi's grip on the west of the country, including the capital Tripoli.
In a significant new deployment of firepower, France and Britain are bringing attack helicopters to use in the strikes in Libya as soon as possible, French Defense Minister Gerard Longuet said Monday.
The use of attack helicopters would appear to mark a new strategy for NATO, which has relied on strikes by fighter planes and seen that result in a stalemate on the ground as Gadhafi forces adapted, often turning to urban fighting to make such strikes more difficult.
Nimble, low-flying helicopters have much more leeway to pick targets with precision than high-flying jets. But they also are much more vulnerable to ground fire. The alliance has had no military deaths since it first started enforcing a no-fly zone on March 31.
Longuet said the helicopters would be used to target military equipment such as Libyan tanker and ammunition trucks in crowded urban areas while causing fewer civilian casualties. Longuet said France would essentially use Gazelle helicopters, which have been around for some 40 years, but can also use the Tigre, a modern helicopter gunship.
The U.S. State Department statement said the visit by Feltman, Assistant Secretary of State for Near Eastern Affairs, was "another signal of the U.S.'s support" for the rebels' National Transitional Council, which it called "a legitimate and credible interlocutor for the Libyan people."
Several countries, including France and Italy, have recognized the NTC, while the United States, Britain and others have established a diplomatic presence in Benghazi.
Feltman plans to meet with council head Mustafa Abdul-Jalil and others before his scheduled departure on Tuesday. He declined to answer questions Monday by a reporter from The Associated Press.
The visit follows the opening of a European Union office on Sunday by that body's top diplomat, Catherine Ashton, who said she looked forward to a better Libya "where Gadhafi will not be in the picture."
Rebel leaders welcome the diplomatic contact, but say only better weapons will help them defeat Gadhafi.
"It is just not enough to recognize (us) and visit the liberated areas," spokesman Abdel-Hafidh Ghoga told AP. "We have tried very hard to explain to them that we need the arms, we need funding, to be able to bring this to a successful conclusion at the earliest possible time and with the fewest humanitarian costs possible."
Rebels now control the populated coastal strip in the country's east and the western port city of Misrata, which Gadhafi's forces have besieged for months. They also control pockets in Libya's western Nafusa mountain range.
Ghoga warned that residents of the Nafusa mountains face a "major humanitarian disaster" because government troops have been cutting supply lines to communities. Rebels say about 225,000 people live in the area.
Col. Jumaa Ibrahim, who defected from Gadhafi's forces and is now a member of the mountain military council, said two villages, Galaa and Yefren, are facing critical shortages. "There is no water, money or food. They are bombed everyday with launchers, tanks and whatever they can," Ibrahim said.
Villagers raise goats and sheep and grow apricots and almonds on the plain near their town, he said. Many fear Gadhafi's troops have destroyed their orchards and stolen or killed their animals.
Gadhafi's forces fired rockets at the mountain town of Zintan on Monday, damaging houses and the tanker trucks residents use to bring in water, resident Hamid Embayah told the AP via Skype. No one was injured.
Faul reported from Benghazi, Libya. Associated Press Writer Ben Hubbard in Cairo and Bouazza Ben Bouazza in Tunisia contributed reporting.