There was no sign of NATO aircraft, whose strikes on Gadhafi loyalists had been crucial to rebel military successes.

Libyan state television showed what it claimed were live images of Gadhafi supporters celebrating in the streets of Ajdabiya, though by nightfall rebels said they had chased most of the loyalists out of town. Fighting continued near the town's western gate, which Gadhafi's forces have pummeled since Thursday with missile strikes and mortar rounds.

Rebels said they captured three Gadhafi loyalists, including a high-ranking military officer, but that could not be confirmed. Fighters also said that a rebel helicopter had been shot down.

The battle appeared to show a rebel movement hanging by a thread, barely able to retain a key gateway to their capital. The opposition forces seemed surprised when Gadhafi's fighters - riding in about 30 pickups, some equipped with Russian-made Grad missile launchers - attacked Ajdabiya from three directions, including the southern desert and two western roads.

The loyalist attack showed the degree to which the Gadhafi forces have adapted to conditions on the ground, where heavy tanks and artillery have become easy targets for NATO jets enforcing a U.N. resolution intended to protect civilians.

Switching to civilian vehicles and light weapons, the Gadhafi forces are now using the same equipmentsas the rebels, confusing NATO air crews and leading to two mistaken NATO airstrikes on rebel positions that killed at least 18 people in the last week.

Rebels said they had begun to paint the tops of their trucks peach to distinguish them from the loyalist pickups, but few rebel vehicles moving toward Ajdabiya on Saturday bore the new marking.

With street battles raging and the explosions of battle heard in the distance, rebel fighters positioned on the desert highway a few miles outside Ajdabiya complained that reinforcements from Benghazi fled at the first sign of a skirmish. As dusk settled, rebels battling to defend Ajdabiya reportedly couldn't distinguish between friendly forces and enemy fighters.

"You can't walk in the streets. You have to hold your ground and stay there because it's not safe," said Saleh Awad Ali, a 40-year-old rebel.

Ahmed Abdul Razaq, an engineer in his 20s, was struck in the neck by a bullet in the middle of the town, according to a cousin, Mohammed al Fakri. While at the small hospital in Ajdabiya, a bullet fired from a distance shattered a window, he said.

But Fakri, a rebel supporter, was confident that "Ajdabiya will be protected by its people."

The day began with surprising reports that rebels had pushed past the oil town of Brega, about 50 miles west of Ajdabiya, which Gadhafi loyalists had controlled for days. But a journey by Abdulkarim Mohammed, a 25-year-old Brega resident who tried to return home early Saturday, suggested that Gadhafi's forces still held the area.

Mohammed said that he was halfway to Brega when he heard machine-gun fire. He retreated east toward Ajdabiya. When he was 11 miles from Ajdabiya, he came under artillery fire, and when he arrived at Ajdabiya's western gate, he saw Grad missiles and rockets coming from the direction of the sea.

Mohammed isn't planning to return to Brega anytime soon.

"It doesn't feel safe," he said.