Two key ISIS-affiliated leaders engaged in a standoff with Philippines forces in the southern city of Marawi have been killed, the country's Defense Secretary Delfin Lorenzana said Monday.

The two leaders were named as Isnilon Hapilon, who was declared terror group's emir for Southeast Asia, and Omar Maute, a leader of a local militant group that had pledged allegiance to ISIS.

Their bodies have been recovered, the Defense Department said in a statement. Seventeen civilian hostages were also rescued, it added. The FBI had offered a reward of up to $5 million for information leading directly to Hapilon's apprehension or conviction for a litany of alleged crimes, including hostage taking, murder, and terrorist activities.