The New Orleans attacker who killed 14 people by ramming a pickup truck into a crowd built two bombs with a “very rare explosive compound”, senior law enforcement officials have said.

The compound had never before been used in a US or European terror attack, with investigators now exploring how attacker Shamsud-Din Jabbar learnt how to produce the explosive.

Jabbar used the compound in two homemade bombs, which were found in coolers on Bourbon Street, where he carried out his deadly attack on New Year’s Day. The bombs did not detonate and it remains unclear whether this was due to a malfunction or lack of activation.

While the FBI has concluded Jabbar was likely not aided by anyone else in the attack, they will now seek to determine if he was taught how to make the explosive devices with the rare compound by an individual or organisation.