With an explosion of gunfire, hugs from worried mothers and wives, and screams of a crowd of thousands, the Muslims of this beleaguered U.N. "safe area" celebrated their liberation from a four-year siege tonight following the smashing of Serb forces by a combined assault of the Croatian and Bosnian armies.

From Bosnia's border with Croatia, through the town of Cazin to this U.N.-protected city on the banks of the Una River, happy Muslims lined a winding mountain road, waving Bosnian flags and cheering the troops of the Bosnian army. Today, that army captured the last piece of enemy-occupied territory in the northern corner of this area known as the Bihac pocket after their forces linked up with attacking Croatian government troops Sunday.

"We did what the United Nations could not do," said Josip Seler, a Croatian soldier who stood today on a bridge connecting Bosnia and Croatia. "We saved the Bihac enclave."

In the town of Cazin, in the heart of the long surrounded Bihac pocket in northwest Bosnia, bedlam ruled the central square as hundreds of soldiers -- wounded, bleeding, their heads swathed in bloody scarves, tired and sunburned -- fell from troop trucks into the arms of a crazed crowd. Children, old men, young girls clutching sagging bunches of sunflowers swarmed to congratulate the soldiers. Some of the troops, from the Bosnian army's 5th Corps, considered the country's toughest, turned their weapons to the darkening sky and fired away. Others collapsed into the arms of loved ones.

One screamed: "Mother, I'm so hungry."

The liberation of Bihac marked the first time in the 40-month-old war in Bosnia that a Muslim enclave has been freed from the withering sieges that have defined the military effort by the Bosnian Serbs. Bihac's freeing came as a direct result of a massive Croatian offensive against rebel Serbs occupying a swath of Croatian territory hemming in this Muslim enclave to the north and west. Bosnian Serb forces are to its south and east.

But if the Croatian offensive was good news for Bihac, the largest of the isolated Muslim enclaves, it is unclear whether it is good news for Bosnia. The Croatian attack ended the Serb occupation of about 3,500 square miles of Croatian land, forcing more than 120,000 Croatian Serbs to flee across the border into Serb-held portions of Bosnia. Among them are an estimated 20,000 soldiers.

U.N. officials said they expect that those soldiers will be mobilized by the formidably armed but lightly manned Bosnian Serb army and then used against the Muslims in Bosnia. Even without the fresh troops, the Bosnian Serbs recently have done well against the largely Muslim Bosnian army, last month capturing the U.N.-designated "safe areas" of Srebrenica and Zepa on the other side of the country.

The Croatian military juggernaut, in a massive attack from five main corridors, freed Bihac from the west, forcing thousands of Serb fighters to flee into Bosnia with just the clothes on their backs. The Croatian offensive, which has captured the whole of the Krajina region, also effectively depopulated an area where Serbs have lived for more than 500 years. U.N. aid officials called that flight the single largest forced exodus since war came to the Yugoslav area in 1991.

But to many of the 180,000 people in Bihac, who have been squeezed by the Serb siege from all directions for more than four years and have suffered nine straight months of Serb attempts to take the pocket, the fate of the Serb refugees appeared fitting retribution for the troubles their army had inflicted upon Bihac.

"I feel for those civilians out there with nothing to eat and no idea of the future," said Murat Tatrevic, 59, a history teacher from Bihac. "But it is so, so nice for once to see my Muslim people have a little good news."

Tatrevic was speaking on a bridge spanning the Koruna River, the historical dividing line between the Austro-Hungarian Empire to the west and the Ottoman Empire to the east -- and where on Sunday Croatian and Bosnian troops linked up in the first major step toward lifting the siege of Bihac.

"I have no words to describe what I feel," said the wizened teacher, who has spent four years fighting for Bosnia.

During that time his house has been destroyed by Serb shellfire, his wife Fanik has lost a leg in another mortar attack and he has dropped more than 25 pounds.

"It's like I'm seeing the sun for the first time since 1992," he said. "Today I have a little hope."

On the bridge, Bosnian and Croatian army soldiers mingled easily. The difference among the men was marked -- although they are all southern Slavs. The Muslim troops were thin, with gaunt faces. The Croatian faces from the Adriatic coast were plump and suntanned. Among the Muslim men, three were on crutches -- all wounded in the war. One man was missing his right calf, another half of his left foot while a third hobbled, with a cast three quarters of the way up his left leg.

Sisters Hata and Bekira Vilic wandered timidly toward the bridge. It was here, they said, that as little girls they played, watched their father catch fish and swam in the cool, shallow waters of the Koruna. Today marked the first time they dared walk on the bridge since May 1992.

Dressed in a T-shirt and a dress fashioned from a worn curtain, Bekira carried an incongruously large daisy to a Croatian soldier and presented him with the gift. "Thank you," she said.

At that point, amid a shattering fusillade, a bus packed with Muslim soldiers rolled up to the bridge, disgorging jubilant men. Just 90 minutes before, the company of an anti-tank unit had been at the forefront of the Bosnian army force that recaptured Velika Kladusa, a town in the northern corner of the Bihac pocket that had been the stronghold of a Muslim rebellion against the Bosnian government since October 1993.

The rebellion, led by renegade Fikret Abdic, is finished, they said, although the whereabouts of the businessman is unknown.