An explosion on Saturday that rocked the crucial Kerch bridge from Russia to Crimea, a hated symbol of the Kremlin's occupation of the southern Ukrainian peninsula, is just "the beginning", President Volodymyr Zelensky's aide Mikhail Podoliak said in Kiev.
The bridge was closed in the early hours of Saturday after a truck exploded, damaging the road and causing a huge fire, RT news reported.
"Crimea, the bridge, the beginning. Everything illegal must be destroyed, everything stolen must be returned to Ukraine, everything occupied by Russia must be expelled," Podoliak said in a tweet.
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Ukrainian officials had earlier threatened to attack the bridge on numerous occasions since Russia launched its ongoing invasion of Kiev on February 24, RT reported.
In August, Podoliak had said that Europe's largest bridge "should be destroyed" because it's "an illegal construction and the main gateway to supply the Russian army in Crimea".
Zelensky and other members of his team have also stated that Ukraine will use force to retake Crimea, which overwhelmingly voted to reunite with Russia in a referendum in 2014, RT reported.
Following the blast at around 6 a.m. on Saturday, images on social media showed a fiercely burning fire engulfing at least two railway carriages from a train on the bridge, accompanied by a vast column of black smoke, reports The Guardian.
The explosion, which witnesses said could be heard kilometres away, took place while a train was crossing the bridge, although it was not immediately clear what caused it.
Some images appeared to show a second fire at some distance from the main blaze.
Later images also appeared to show part of road bridge that runs parallel with the train tracks had collapsed, The Guardian reported.
The bridge is both highly symbolic to Russia and an important logistical supply route for Russian forces in Crimea and in southern Russian-occupied Ukraine.
The Russian news service TASS said a fuel tanker was involved.
"According to preliminary data, a fuel tank (railroad) car has been on fire at one of the sections of the Crimean bridge, shipping arches aren't damaged," said Oleg Kryuchkov, an adviser to the Russian occupation head of the Crimea.
Another Moscow-appointed official said: "A cistern carriage is burning with fuel on one of the bridge sections. Shipping arches aren't affected. Too early to talk about reasons and consequences. Work is under way to put out the fire."
However, video footage taken from the road span appeared to show fires burning fiercely in several railway trucks along the length of the train, numbering at least half a dozen with the train stationary on the bridge, The Guardian reported.
The railway span is part of a pair of parallel bridges, crossing the Kerch Strait linking Krasnodar in Russia and Crimea, which was built by Russia after its invasion and annexation of Crimea in 2014.