The Federal Bureau of Investigation and the U.S. Department of Homeland Security on Monday warned of a potential public safety threat from violent extremists who might try to copy the New Year's Day attack in New Orleans that killed 14 people.
The warning comes a week before U.S. President-elect Donald Trump's Jan. 20 inauguration.
"The FBI and DHS are concerned about possible copycat or retaliatory attacks due to the persistent appeal of vehicle ramming as a tactic for aspiring violent extremist attackers," the agencies said in a statement.
Early on New Year's Day, more than a dozen people were killed and a dozen others injured when a man rammed a rented pickup truck into a crowd of revelers along Bourbon Street in New Orleans.
The man who carried out the attack was a U.S. Army veteran who had pledged allegiance to Islamic State and appeared to have made recordings condemning music, drugs and alcohol.
The agencies said such attacks, inspired by foreign "terrorist" organizations, have been carried out in the U.S. and abroad using rented, stolen and personally owned vehicles.
Attackers could also attempt to use improvised explosive devices to supplement a vehicle attack, they said.
The agencies said past targets have included pedestrians, law enforcement or military members, and crowded public venues that are accessible from roadways.
"We ask that the public remain vigilant regarding possible copycat or retaliatory attacks and report any suspicious activity to law enforcement," they said.
