The head of Russia’s FSB security agency Alexander Bortnikov said Tuesday that the 4 suspects who have been captured were heading to Ukraine and would have been "greeted as heroes," despite the agency not having confirmed who "ordered the attack.

"We believe the action was prepared both by the radical Islamists themselves and, of course, facilitated by Western special services, and Ukraine’s special services themselves have a direct connection to this," Bortnikov said, per Barron’s.