ASUNCION, Paraguay - Authorities filed manslaughter charges Tuesday against an owner of a Paraguayan supermarket that caught fire, killing at least 464 people, local media reported.

The indictment in Paraguay's worst disaster in decades came after investigators said a security guard told them that when Sunday's fire broke out, the doors were ordered locked to prevent looting.

Supermarket owner Juan Pio Paiva denied that the doors had been deliberately locked and said the building met safety codes.

Channel 13 television reported that a judge had charged Pio Paiva with involuntary manslaughter and ordered him imprisoned while the investigation moved forward. Court officials refused to comment on the decision.

Earlier Tuesday, the death toll soared as the attorney general's office said 464 had been killed, up from the 325 reported earlier. Officials also said 409 people remained hospitalized.

Dozens of families were still searching for lost loved ones as investigators questioned the store's two owners, a manager and four security guards over whether the doors had been ordered locked to stop people from leaving without paying - allegedly trapping shoppers inside.

The blaze broke out during lunch hour at the three-story supermarket in a suburb of Asuncion, the capital. Flames quickly spread through the Ycua Bolanos supermarket, food court and parking garage, causing a floor to collapse. Officials say they are checking reports an exploding gas canister could have started the flames.

Prosecutor Edgar Sanchez, who is leading the investigation, said a security guard told authorities that at the outset of the fire he received orders over a radio to lock the doors to prevent theft.

Sanchez said the guard "didn't know" who gave the order. "He couldn't identify the voice that spoke to him over the radio," the prosecutor said.

In addition to Pio Paiva's arrest, authorities have also taken into custody for questioning his son who is a co-owner, a business associate and four security guards.

Officials said they were trying to piece together survivor claims that locked doors might have impeded or slowed shoppers trying to escape.