Fire roared through a multilevel supermarket on the outskirts of Paraguay's capital Sunday, causing at least one floor to collapse. The government said at least 256 people were killed and they expected the toll to rise.

One television station said at least 340 bodies had been recovered.

The fire broke out at the Ycua Bolanos supermarket while it was crowded with midday shoppers. It swept through the complex, which housed a food court, supermarket and parking garage.

Interior Minister Orlando Fiorotto said late Sunday night that rescue workers had pulled 256 bodies from the charred building and were still counting bodies being brought in.

Paraguay's Channel 9 television reported that 340 bodies had been recovered, citing unofficial accounts by rescue workers and police.

Officials were still trying to determine the cause of the fire as the building continued smoldering after nightfall.

President Nicanor Duarte visited the scene and declared three days of national mourning to begin Monday.

Badly burned bodies, their limbs twisted, were carried away on stretchers. Officials appealed for blood donations and medical supplies as hospitals went on emergency staffing throughout the capital of this small, impoverished South American nation.

Rescue workers wearing masks helped remove victims on stretchers as riot police kept back a growing crowd. The victims included a baby and a pregnant woman.

One woman, her face covered with soot, sobbed as she was carried away on the shoulders of a rescue worker. Firefighters battled through smoke to get inside the market and carry out other victims.

Fiorotto ordered off-duty police and firefighters to the scene and urged hospitals to prepare for the injured. Hundreds of neighbors living nearby rushed to the scene, helping to carry bodies from the building as firefighters held water hoses. Dozens of relatives crowded outside and cried as bodies were pulled out.

Some burned bodies could be seen seated upright in cars in a first-floor parking lot, blackened by the intense heat. A towering column of black smoke billowed from the pink-and-white building lined by palm trees.

District police commander Aristides Cabral said an explosion reportedly was heard before fire swept through the building.

"There was an explosion inside and the heat forced the bottom floor supporting the basement to give way, crushing dozens of people," he said.

Francisco Barrios, a shopper who escaped the blaze, described a confusing scene minutes after the fire started, with people rushing for the doors.

"There were sparks as if fireworks were going off. The store quickly caught fire and filled with smoke, triggering total confusion," he said, crying. "I lost my wife and kids as I rushed to get out. Now I'm desperately trying to find them."

Smoke rises from a retail complex in a suburb of Paraguay's capital, Asuncion, which erupted in fire while crowded with shoppers.A firefighter carries a crying victim who had been trapped inside the Ycua Bolanos supermarket. Hundreds of people living nearby also rushed to the scene to help.