The authorities have said they do not believe the suspect, Shamsud-Din Bahar Jabbar, a 42-year-old Army veteran, acted alone. The police said Mr. Jabbar died in a shootout with officers after he drove the truck into revelers on Bourbon Street in the city’s French Quarter in the early hours of New Year’s Day.

Fourteen people were killed and at least 35 injured in what authorities called a terrorist attack in New Orleans.