India, April 16 -- The wood-and-lead spire on the top of the iconic Notre Dame Cathedral has collapsed after a massive fire ripped through the centuries-old structure in the heart of Paris on Monday evening.

The moment the spire folded over into the building engulfed in flames amid plumes of white smoke billowing into the sky was captured in a video as onlookers gasped at the sight.

Thousands of Parisians and stunned tourists watched disbelief as the inferno raged at the cathedral, which sits on the Ile de la Cite, an island in the River Seine. The onlookers, some sang Ave Maria and others kneeled and prayed, lined bridges over the Seine and along its embankments, held at a distance by a police cordon.

WATCH| Spectators gasp as Notre D...