Witnesses reported a "suspicious package" being dropped off by a person riding a taxi around 2 am. The IED was found inside a carton box on the sidewalk of Roxas Boulevard, near the US embassy. The explosive was composed of a blasting cap, a detonator, a cellular phone, and a 9-volt battery. Police said the box also contained an 81-mm mortar, similar to the one found in the September explosion at a Davao night market. Police chief Director General Ronald dela Rosa said the bomb try was an "attempted act of terrorism” by the Lanao del Sur-based Maute terror group, which has pledged allegiance to the Islamic State (ISIS).