PARIS, April 16 -- Paris public prosecutor Remy Heitz on Tuesday said the blaze at Notre Dame Cathedral was probably caused by accident as no signs "at this stage" pointed to a criminal purpose.

"I say very clearly that nothing at this stage is going in the direction of a voluntary act," Heitz told reporters, adding that they are favoring the theory of an accident.

"At this point, experts can not have access to the site. The investigations are just beginning," he said.

The inquiry to determine how the fire broke out would be "long and complex", he warned, pledging that "all means are implemented to know the truth, to know the origin of this terrible fire."

The Paris prosecutor added about 15 workers of five companies that participated in the cathedral's massive renovation project were questioned by police.

The devastating fire at Notre Dame Cathedral in central Paris has been put out after burning for 15 hours, local media reported on Tuesday.

According to the official Paris fire service Twitter account, nearly 400 firefighters attended the scene, while "2 police officers and a firefighter were slightly injured."