Two Americans were killed in an attack in Nice, France, Thursday night, after a driver plowed into a large crowd with a truck hauling grenades and other weapons during Bastille Day celebrations, the U.S. State Department said.
Police identified the attacker as Mohamed Bouhlel, a 31-year-old Tunisian living in Nice, and said he had drawn a gun on them. The front windshield of the truck was covered with bullet holes.
Officials did not name the two Americans, although family members confirmed their identifies to ABC News.
"We are aware that two U.S. citizens were killed in the attack. We are working with local authorities to determine if other U.S. citizens were injured in the event," according to a statement released by the State Department this morning. "We strongly urge U.S. citizens in Nice to be in direct contact with your family members in the United States and elsewhere to advise them of your safety."
Sean Copeland and his 11-year-old son Brodie, who were in Nice on a family vacation, were killed in the attack, Alyssa Weaver, the elder Copeland's niece, wrote on Twitter. The Copelands are from Lakeway, Texas, about 30 miles west of Austin.
Weaver tweeted, "I am asking for prayers for my family, due to the tragedy in Nice, France I lost my uncle Sean and my 11 year old cousin Brodie I ask for prayers for my aunt Kim and my two other cousins Maegan and Austin during this tough time and prayers for my family’s safe trip back home #CopelandStrong”
The death toll climbed overnight from 80 to 84 people, including several children, as dozens more were injured and receiving treatment, according to the Ministry of the Interior.
"France is horrified by what has just occurred -- a monstrous act of using a truck to intentionally kill dozens of people celebrating 14th of July," French President Francois Hollande said during a nationally televised address early today. "France is strong. France will always be stronger than the fanatics who want to strike France today."
There have been no claims of responsibility. The Paris anti-terrorism prosecutor's office was put in charge of the investigation.
Mohamed Bouhlel, the man who carried out the truck attack in Nice was a Tunisian living in the city, the Associated Press reports, citing two French officials. The officials confirmed that the ID found in the truck matched the dead attacker.
They said Bouhlel was living legally in France. Tunisia is a former French colony.
Hollande extended the country's state of emergency for three months and was mobilizing reservists. He said it was unclear whether the attacker had any accomplices.
Graphic images surfaced on social media showing the chaos that ensued, including the truck barreling over crowds as dozens were seen running from the scene.
The Vatican released a statement this morning condemning the attack.
"Throughout the night we have followed with great concern the terrible news from Nice. On behalf of Pope Francis, we join in solidarity with the suffering of the victims and of the entire French people this day that should have been a great holiday," Vatican spokesman the Rev. Federico Lombardi said in a statement. "We condemn in the strongest way every demonstration of senseless violence, of hatred, terrorism and any attack against peace."
Pope Francis also tweeted this morning that he was praying for the victims.
Secretary of State John Kerry, who joined French leaders Thursday at Bastille Day celebrations in Paris, said he would continue to stand "firmly" with the French people during this time.
French Prime Minister Manuel Valls said the government is declaring three days of national mourning following the attack in Nice.
Vallas said the national mourning would begin Saturday.
Information from the Associated Press was used in this report.