JIM LEHRER: The air campaign across Libya zeroed in today on ground forces, after sweeping the skies of planes. The aerial pounding forced government troops and tanks to pull back from Misrata, before reports of new fighting hours later. And south of Tripoli, rebels in Zintan said government fighters retreated from all but one side of the city.
We get more from Martin Geissler of Independent Television News, beginning with the day's developments in eastern Libya.
MARTIN GEISSLER: A new wave of fighting in Ajdabiya today triggered fresh energy among the rebels here and another push to the front. There were reports and signs of heavy shelling in the town. Some residents, though, did manage to escape from what they say is a living hell.
MAN: Gadhafi, Gadhafi's bomb.
MARTIN GEISSLER: He's bombing...
MAN: Many homes were destroyed, the hospital -- even the hospital destroyed, mosques, schools.
MARTIN GEISSLER: In the west, the crisis in rebel-held Misrata worsened today with reports of snipers firing in the city center. One doctor told ITV News they attacked his clinic.
The allies airstrikes continued for a fourth day. This was the scene in Anzara, a Tripoli suburb said to have been targeted by allied planes overnight. There were reports of strikes on Misrata, too. The British commander coordinating the operation says the Libyan air force is now defeated.
AIR VICE-MARSHAL GREG BAGWELL, U.K. Royal Air Force: We are now applying sustained and relenting pressure on the Libyan armed forces. Their air force no longer exists as a fighting force.
MARTIN GEISSLER: But Gadhafi's supporters were buoyed by a stirring speech from their leader tonight. One news reader on state TV offered to sacrifice his last breath, last drop of blood and last baby. Across Libya, many have paid that price unwillingly.
This started as a peaceful protest, but, in the past five weeks, it's descended into carnage, with an ever-increasing civilian death toll. This is not how Libya's revolution was meant to be.
The outcome is still far from certain, but having come this far, there is no going back.
GWEN IFILL: As Wednesday night fell in Tripoli, explosions echoed across the city again, apparently from new airstrikes.
In Washington, Secretary of State Hillary Clinton said Gadhafi could end the fighting by leaving Libya. But Defense Secretary Robert Gates said there's no telling what the Libyan leader's fate will be.
He spoke during a visit to Egypt.
SECRETARY OF DEFENSE ROBERT GATES: I think there are any number of possible outcomes here, and no one's in a position to predict them. Whether there are major defections, further major defections within his own ruling circle, whether there are divisions within his family, there are a variety of possibilities, it seems to me.
JIM LEHRER: The U.S., European, Arab and African nations planned to meet next week on control of the no-fly zone over Libya.
In the meantime, NATO warships began patrolling off the Libyan coast, enforcing a U.N. arms embargo.