The bridge was closed earlier after a fuel tank caught fire.
The bridge that connects the Crimean Peninsula with mainland Russia has been damaged by a truck bombing, the National Anti-Terrorism Committee said on Saturday.
Officials said that the blast, which occurred shortly after 6am local time, caused a partial collapse of the road on the vehicle section. It also triggered a blaze on a freight train on the parallel rail section, with seven fuel tanks catching fire.
“The arch above the shipping section of the bridge has not been damaged,” the committee added.
An unverified video appears to show the moment of the blast.
A video from the scene that was posted on social media appears to show the fuel tank fire and the damage to the road.
Nikolay Lukashenko, the acting regional transport minister, told reporters that the authorities are considering launching a ferry service.
The 19-kilometer (11.8 mile) bridge, which runs across the Kerch Strait and connects Crimea with mainland Russia, consists of a railway section and a vehicle section. It became fully operational in 2020.