It was around 06:00 Saturday morning local time that Ukrainian media reported an explosion on the Crimean Bridge, which links the Russian-annexed Crimean peninsula with the Russian mainland.

The bridge, which stretches nearly 19 kilometers across the Kerch Sound and is considered to be Europe's longest road and rail bridge, started to burn heavily at the same time as parts of the structure collapsed.

It is still unclear what caused the explosion, which has caused all traffic across the strait to be stopped.

According to information from the Russian state news agency Ria, a fuel tank has exploded on a train, which is said to have been caused by a car bomb, the news agency said.

The Crimean Bridge connects the Crimean Peninsula with the Russian mainland and is about 19 kilometers long.

Photo: SVT

However, nothing has yet been confirmed by independent sources and theories about what could be behind the explosion differ.

"Will certainly be questioned

Russia expert Martin Kragh, who is deputy director of the Center for Eastern European Studies and senior researcher at the Foreign Policy Institute (UI), tells TT that it may well be Ukraine that succeeded in attacking the bridge with, for example, rocket fire.

- What I see now is that the official Russian side insists that it could be some type of car bomb.

But that view will surely be questioned when more information comes to light, says Martin Kragh.

Pictures and videos that have been circulated of the explosion show extensive material devastation.

The two roadways and the railway tracks are said to be destroyed where the explosion occurred.

So far, three people have been found dead, Reuters reports citing Russia's Investigative Committee.

"Heavy blow to Russian capability"

As of lunchtime on Saturday, no one had yet claimed responsibility for the incident.

But according to defense experts, the Crimean bridge is of great military strategic importance to Russia as it makes it possible to supply Russian units with material.

- This is a hard blow to Russian ability.

This is the lifeline from Russia to the Crimean peninsula, says Joakim Paasikivi, lieutenant colonel and teacher of military strategy at the Norwegian Defense Academy.

President Volodymyr Zelenskyi's adviser, Michajlo Podoljak, wrote on Twitter on Saturday morning that "This is just the beginning," referring to the explosion on the Crimean bridge.

"Everything illegal must be destroyed, everything stolen must be returned to Ukraine, everything occupied by Russia," he writes further.