Ajdabiya, Libya (CNN) -- The retreat of Moammar Gadhafi's forces from a key eastern city Saturday reinvigorated the opposition, which began taking the fight west toward the capital of Tripoli.
By Saturday evening, advancing opposition fighters had reached the outskirts of the city of Brega, to the west of Ajdabiya, said opposition spokesman Col. Ahmed Omar Bani.
"The winds of change are starting to blow," Bani told reporters in Benghazi.
Gadhafi's troops fell back after days of fierce fighting in Ajdabiya, Libyan Deputy Foreign Minister Khaled Kaim told reporters. He said the coalition's airstrike attacks were direct and the Libyan military decided to withdraw.
That air campaign continued Saturday, further limiting loyalist movements. French warplanes destroyed at least five Libyan combat planes and two helicopters over a 24-hour period, the Ministry of Defense said.
Meanwhile, an especially loud explosion and the subsequent sound of a plane, most likely belonging to the allies, were heard late Saturday in Tripoli, but there was no anti-aircraft fire in response.
After the fall of Ajdabiya, the fighting is sure to shift westward through cities and towns that are more loyal to Gadhafi.
Jalal al-Gallal, another spokesman, said the opposition expects heavy resistance in towns like Sirte, Gadhafi's birthplace, where he has strong support.
Gadhafi's forces resumed shelling Misrata, just two hours east of Tripoli, where some of the most intense fighting has taken place since protests erupted in Libya last month.
A witness told CNN that Gadhafi troops randomly targeted buildings and people in Misrata. Another witness said he saw busloads of loyalist snipers being brought to the city. CNN could not independently verify those accounts.
Officials have said Gadhafi is far from defeated and still retains the power to reinforce units.
Opposition fighters chanted gratitude for the coalition's support after they wrested control of Ajdabiya, considered a gateway to Libya's vast oil fields and a stopping point en route to the rebel stronghold of Benghazi.
They were confident that with protective air power they would be able to hold onto the city they had captured once before but lost to Gadhafi's army.
Ajdabiya is now "100 percent" in opposition hands, said Shamsuldin Abed Mawlah, spokesman for Libya's opposition interim council. He said many loyalists were retreating westward.
Overnight, international fighter jets again bombed Libyan tanks that have been entrenched at the city's northern and western gates for days, said al-Gallal.
At the northern entrance, damaged tanks lay strewn across the rolling desert. The buildings around the city entrances were riddled with bullet holes. Rebel troops combed the city's streets Saturday, hunting for any remaining Gadhafi loyalists as some displaced residents trickled back to their homes.
The Ajdabiya victory is viewed as significant for the opposition. It also served as evidence of the impact of coalition airstrikes as NATO prepares to take command of the Libya mission this weekend.
Coalition airstrikes targeted Gadhafi's military on the outskirts of Misrata but tanks resumed shelling Saturday, a doctor at the main hospital told CNN. Opposition fighters, armed only with light weapons, were trying to repel the attack and casualties were mounting, he said.
At least 20 people were wounded in Misrata, victims of snipers taking aim in the heart of the city, said the doctor, who was not identified for safety reasons. Friday, seven people were killed and another 70 were wounded.
Al-Gallal said the next big battle will be for control of Misrata.
"He (Gadhafi) is scared about Misrata," al-Gallal said. "It's too close to Tripoli. He's going to do everything he can to hold on to it."
Opposition leaders uploaded a video that showed a rooftop view of Misrata. Gunfire could be heard and puffs of smoke rose from at least one rooftop, possibly indicating a sniper. CNN could not verify the contents of the video.
Coalition planes flew 164 sorties Friday in Operation Odyssey Dawn and coalition leaders reported damage to Gadhafi's ground forces.
"Coalition forces have targeted anti-air capabilities, tanks, armored vehicles, as well as other regime forces threatening the civilians throughout the country," said Capt. Clint Gebke, a coalition spokesman.
U.S. President Barack Obama defended America's leadership in the international coalition in his weekly radio address Saturday.
"Make no mistake," Obama said, "because we acted quickly, a humanitarian catastrophe has been avoided and the lives of countless civilians -- innocent men, women and children -- have been saved."
"The United States should not -- and cannot -- intervene every time there's a crisis somewhere in the world," Obama said.
"But I firmly believe that when innocent people are being brutalized; when someone like Gadhafi threatens a bloodbath that could destabilize an entire region; and when the international community is prepared to come together to save many thousands of lives -- then it's in our national interest to act. And it's our responsibility. This is one of those times."
Obama is scheduled to deliver a televised address on Libya Monday evening.
Libyan government spokesman Ibrahim Mussa slammed the coalition attacks.
"This is immoral, illegal and it was not authorized by the (United Nations) Security Council," he told reporters in Tripoli.
Libyan state television reported Saturday that "airstrikes from the enemy" had hit military positions in Tarhunah, about 40 miles (66 kilometers) from the country's capital.
Pentagon spokesman Capt. Darryn James told CNN Saturday that airstrikes had struck military targets along the Libyan coast, including those in the capital.
CNN's Arwa Damon, Nic Robertson and Reza Sayah contributed to this report