Fire roared through a multilevel supermarket on the outskirts of the Paraguayan capital Sunday, causing at least one floor to collapse, and the government said at least 256 people died but that toll was expected 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 Sunday midday shoppers, sweeping through the multilevel complex that houses a food court, supermarket, and parking garage.

Interior Minister Orlando Fiorotto (search) 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 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 (search) visited the scene and declared that three days of national mourning would begin Monday.

"This is a moment of great anguish," Duarte said. "I've come here to provide support to the injured and the families of the deceased."

Badly burned bodies, their limbs twisted, were hustled off on stretchers. Public 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.

Police at hospitals held back sobbing relatives as the wounded, some covered in foil blankets, were rushed into emergency rooms on stretchers.

Several levels of the multilevel supermarket were covered in soot, including a lower level parking garage where cars were crushed and burned.

"I'm looking for my mother. Has anyone seen her?" one unidentified man cried on Paraguayan television, holding up a photograph. "She went shopping this morning and I've checked everywhere and cannot find her."

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. An Associated Press photographer at the scene said hundreds of neighbors living nearby rushed to the scene, helping 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.

Hundreds of rescue workers, bystanders and relatives stood outside the shopping complex, located in an Asuncion suburb. Brown smoke filled the air for hours afterward.

Public Health Minister Julio Cesar Velazquez (search) told reporters, "I have never seen a disaster like this. The firefighters were taking out, as best as they could, the bodies, the injured and people suffering from smoke inhalation. It's horrible."

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."