TRIPOLI, Libya (AP) -- NATO airstrikes targeted the center of Moammar Gadhafi's seat of power early Monday, destroying a multistory library and office in his compound and badly damaging a reception hall for visiting dignitaries.
Gadhafi's whereabouts at the time of the attack on his sprawling Bab al-Aziziya compound were unclear. A security official at the scene said four people were lightly hurt.
Monday's strike came after Gadhafi's forces unleashed a barrage of shells and rockets at the besieged rebel city of Misrata in an especially bloody weekend that left at least 32 dead and dozens wounded.
The shelling of the only major city in western Libya in rebel hands continued early Monday morning, destroying two schools in the Abbad neighborhood. Residents said the attack lasted about an hour and they found what is believed to be a remnant of a 155mm shell.
The battle for Misrata, which has claimed hundreds of lives in the past two months, has become the focal point of Libya's armed rebellion against Gadhafi since fighting elsewhere is deadlocked.
Video of Misrata civilians being killed and wounded by Gadhafi's heavy weapons, including Grad rockets and tank shells, have spurred calls for more forceful international intervention to stop the bloodshed.
In Brussels, a NATO spokesman said the alliance is increasingly targeting facilities linked to Gadhafi's regime with government advances stalled on the battlefield.
"We have moved on to those command and control facilities that are used to coordinate such attacks by regime forces," the spokesman said of the strike on Bab al-Aziziya, which has been hit last month, early in the NATO air campaign. The official spoke on condition of anonymity in line with military briefing regulations.
Gadhafi's son, Saif al-Islam Gadhafi, struck a tone of defiance. He claimed Gadhafi has "millions of Libyans with him" and said NATO's mission was doomed to fail.
"In history, no country has achieved victory with spies and traitors and collaborators. ... NATO, you are the losers," he was quoted as saying by the state news agency JANA.
In Washington on Sunday, three members of the Senate Armed Services Committee said more should be done to drive Gadhafi from power, including targeting his inner circle with airstrikes. Gadhafi "needs to wake up every day wondering, 'Will this be my last?"' Sen. Lindsey Graham, a Republican on the committee, told CNN's "State of the Union."
In last month's attack on Bab al-Aziziya, a cruise missile blasted an administration building, knocking down half of the three-story building. The compound also was targeted in a U.S. bombing in April 1986, after Washington held Libya responsible for a blast at a Berlin disco that killed two U.S. servicemen.
At least two missiles struck Bab al-Aziziya early Monday, and the booms could be heard miles (kilometers) away.
A multistory building that guards said served as Gadhafi's library and office was turned into a pile of twisted metal and broken concrete slabs. Dozens of Gadhafi supporters climbed atop the ruins, raising Libya's green flag and chanting support for their leader.
A second building, where Gadhafi received visiting dignitaries, suffered damage. The main door was blown open, shards of glass were scattered across the ground and picture frames were knocked down.
Just two weeks ago, Gadhafi had received an African Union delegation led by South African President Jacob Zuma in the ceremonial building, which was furnished with sofas and chandeliers. The delegation had called for an immediate cease-fire and dialogue between the rebels and the government.
NATO's mandate from the U.N. is to try to protect civilians in Libya, split into a rebel-run east and a western area that remains largely under Gadhafi's control. While the coalition's airstrikes have delivered heavy blows to Gadhafi's army, they have not halted attacks on Misrata, a city of 300,000 people.
Still, in recent days, the rebels' drive to push Gadhafi's men out of the city center gained momentum.
Late last week, they forced government snipers out of high-rise buildings. On Sunday, rebels took control of the main hospital, the last position of Libyan troops in the center of town, said a resident who asked to be identified only by his given name, Abdel Salam, for fear of reprisal. Throughout the day, government forces fired more than 70 rockets at the city, he said.
"Now Gadhafi's troops are on the outskirts of Misrata, using rocket launchers," Abdel Salam said.
A Misrata rebel, 37-year-old Lutfi, said there had been 300-400 Gadhafi fighters in the main hospital and in the surrounding area that were trying to melt into the local population.
"They are trying to run way," Lutfi said, speaking on condition of anonymity for fear of reprisal. "They are pretending to be civilians. They are putting on sportswear."
Ali Misbah, a captured Libyan soldier who had been wounded in the leg, was held under guard in a tent in the parking lot of the Al Hikmeh Hospital, one of the city's smaller medical centers.
Misbah, 25, said morale was low among Gadhafi's troops. "Recently, our spirit has collapsed and the forces that were in front of us escaped and left us alone," he said.
Misbah said he and his fellow soldiers were told that they were fighting against al-Qaida militants, not ordinary Libyans who took up arms against Gadhafi.
"They misled us," Misbah said of the government.
A senior Libyan government official has said the military is withdrawing from the fighting in Misrata, ostensibly to give a chance to tribal chiefs in the area to negotiate with the rebels. The official, Deputy Foreign Minister Khaled Kaim, said the tribal chiefs were ready to send armed supporters to fight the rebels unless they lay down their weapons.
Rebels on Sunday dismissed government claims that tribes in the area were siding with Gadhafi and that troops were redeploying voluntarily.
"It's not a withdrawal. It's a defeat that they want to turn into propaganda," said Dr. Abdel-Basit Abu Mzirig, head of the Misrata medical committee. "They were besieging the city and then they had to leave."