Five Russians were among those taken into custody while the other suspects were described as Ukrainian and Armenian, said a statement by the FSB, which is Russia's version of the CIA.
The intelligence agency did not reveal other details but did echo allegations made by Russian President Vladimir Putin, who has continued to blame the Kyiv government for the deadly blast on the 12-mile Kerch Bridge, where a truck exploded Saturday and ignited a huge fire.
Since Monday, Russia has unleashed a barrage of deadly retaliatory airstrikes throughout Ukraine, the latest which happened Wednesday as seven people were reportedly killed and eight other injured at a market in the eastern town of Avdiivka.
Shelling in Nikopol, in the Dnipro region, seriously injured three civilians, including a 6-year-old girl, according to a spokesperson for Ukrainian President Volodymyr Zelensky.