PARIS (AP) — The Paris prosecutor’s office says that there is no evidence from a preliminary investigation to suggest that a fire that destroyed large parts of Notre Dame Cathedral was criminal.

The prosecutor’s office said in a statement on Wednesday that several hypotheses about the cause of the April 15 blaze include a malfunctioning electrical system or a smoldering cigarette.

The prosecutor’s office announced the opening of a new investigation for “involuntary degradation by fire through manifestly deliberate violation” of security rules or simple imprudence. Three judges will head the probe.

The fire tore through the roof of the 13th-century cathedral, destroying the spire which toppled in flames and sections of the interior. It has left the crippled monument, once a major tourist attraction, barricaded to the public.