Russian sources alleged that the explosion that shook the 18-km bridge connecting mainland Russia to the Crimean peninsula Saturday morning was caused by a Ukrainian car bomb.

Three people were killed in the incident, with parts of the bridge igniting in flames and others completely destroyed. Half the bridge collapsed following the attack, cascading into the water below.

A supply train headed for Crimea was engulfed with flames as a result of the attack. A spokesman for the Russian Federation said the blast ignited seven fuel tanks, leading to the collapse of two roads on the bridge.

The bridge is a tactical asset for Russia, ensuring it maintains a physical link to occupied Crimea, which Ukraine claims as its sovereign territory and has vowed to liberate from Russian forces.

The blast may have been the first step in a Ukrainian military push towards the occupied peninsula, as forces continue making progress against Russian troops in the south and east of the country.

Video: Guardian News