KYIV, Ukraine (AP) — Authorities say a small explosive device carried by a makeshift drone blew up Sunday at the headquarters of Russia’s Black Sea Fleet on the Crimean Peninsula, wounding six people. The attack prompted the cancellation of ceremonies honoring Russia’s navy there. There has been no immediate claim of responsibility. But the seemingly improvised, small-scale nature of the attack raised the possibility that it was the work of Ukrainian insurgents trying to drive out Russian forces. In other developments, one of Ukraine’s richest men, a grain merchant, has been killed in what Ukrainian authorities say was a carefully targeted Russian missile strike on his home.