The question New Orleans investigators hope to answer: will there be another attack?

The FBI believes the attacker acted alone, but he has been linked to Islamic State and such violence tends to cluster

As investigators examine the terrorist attack in New Orleans on Wednesday, they will be hoping to answer three questions: who was responsible, how was the attack executed, and why? All will be vital to answering the most pressing question of all: will there be another attack in the immediate hours or days to come?

Their first priority will have been to identify the attacker. The FBI has said it believes Shamsud-Din Jabbar, the 42-year-old who drove a pickup truck into a crowd celebrating the new year, acted alone. He hired a vehicle and procured an assault rifle, as well as body armour and ammunition. He also fabricated what appeared to be several pipe bombs containing plastic explosives, which he may have positioned to target police.