Photos and videos published across social media showed parts of the bridge, including the outer pedestrian walkway, breaking off and falling into the Tiber river it spans.
— Simone Arduini (@simone_arduini) October 2, 2021
The fire brigade said in a tweet on Sunday that it was able to put out the fire by 4am.
It declared the bridge unusable, also banning the transit of boats along that stretch of the river.
#Roma, #incendio Ponte dell’Industria: concluso alle 4 l’intervento dei #vigilidelfuoco, dichiarato inagibile il ponte e interdetto anche il transito dei natanti sul tratto del fiume #Tevere #3ottobre pic.twitter.com/eKnG4iC4CL
— Vigili del Fuoco (@emergenzavvf) October 3, 2021
No-one was injured in the fire, but three nearby nightclubs were evacuated as a precaution, according to the Irish Examiner.
Some external parts of the bridge collapsed in the fire, but the underlying structure remained intact, Italian news website Tgcom24 reported.
The service tunnels at the sides and the sections overlooking Radio Square were particularly badly damaged, it added.
The flames also affected surrounding vegetation and some makeshift shelters below the bridge, occupied by homeless people.
Media reports indicated that the fire may have originated there, possibly started by the explosion of a cooking gas canister. However, the fire brigade ruled out arson.
The fire also affected a gas pipeline and several electrical cables under the bridge road, causing a blackout in parts of the Trastevere and Ostiense districts of the capital.
Traffic was also impacted as the bridge connects two key areas of the city – Marconi and Ostiense.
“What we can say at the moment is that it is heartbreaking to see a piece of history reduced to this. The municipal committee was called to see to the gas and electricity services on Sunday morning. Then we need to look at structural stability. After that, we will try to work on reopening the roads,” Mayor Virginia Raggi said in a live video on Facebook.
The historic bridge was built between 1862 and 1863 and is 131 metres long.