PARIS (AP) — French emergency workers found a body Tuesday in the rubble of a Paris building whose facade collapsed in an explosion last week and are working to remove the remains and identify the person, the Paris prosecutor’s office said.

The discovery marks the first fatality in the blast, which left six people critically injured and more than 50 people with lighter injuries or psychological shock, according to the Paris prosecutor.

Authorities had been digging through debris for days to try to locate a person reported missing since the explosion June 21. The search was complicated by the risk that a neighboring building could also collapse.

The identity of the person whose body was found Tuesday was not yet clear, according to the prosecutor’s office.

After the discovery, the preliminary investigation opened into the case was expanded to include potential manslaughter charges, the prosecutor's office said. Prosecutors are looking into whether the explosion was caused by intentional violation of safety rules. A possible gas leak was one of the theories under investigation.

The French capital’s historic — and sometimes ageing — infrastructure has seen occasional gas explosions in the past. Last week's explosion near the historic Val de Grace military hospital in the city's 5th district crumpled the facade of a building that held a private academy of design and arts.