The fire that broke out at the Cathedral of Notre-Dame in Paris, destroying its spire and severely damaging its roof, was extinguished Tuesday morning.

What we know about the fire

• Rémy Heitz, the Paris prosecutor, said that a first fire alarm was triggered at 6:20 p.m. Monday, but that no fire was found after checks were carried out.

• A second alarm was triggered at 6:43 p.m., and a fire was found under the roof in a network of wooden beams, many dating from the Middle Ages, that is nicknamed “the forest.”

• No one was killed, officials said, but a firefighter and two police officers were injured.

• Investigators were treating the fire an accident, Mr. Heitz said. “Nothing at this stage suggests a voluntary act.” His office said on Tuesday night that “about 30 witnesses,” including workers from companies involved at the construction site and Notre-Dame security staff, had been questioned so far.