One of the two slain gunmen, who carried out the attack on the Bardo National Museum that killed at least 19 people, was previously known to Tunisian security forces.
Yassine Labidi and Saber Khachnaoui were identified as the gunmen, according to Tunisian Prime Minister Habib Essid. It has not been determined to which organization they belong to.
The Tunisian government is currently searching for up to three other suspects, who are possibly involved in the attack, that injured more than 40 people on Wednesday.
Two Tunisians were killed in the attack, including a security officer. The majority of people killed, 17, were foreign tourists from Japan, Italy, Colombia, Spain, Australia, France and Poland.
Tunisia is seen as one of the few, if only, success stories of democracy thanks to the Arab Spring movements, which focused on removing oppressive leadership.
White House Press Secretary Josh Earnest said the United States is prepared to assist in the investigation, stating pride in the "robust cooperation" with Tunisia against counterterrorism and other issues.
"We extend our deepest sympathies to the victims of today's heinous violence in Tunisia and condemn in the strongest terms this terrorist attack, which took the lives of innocent Tunisians as well as visiting tourists," Earnest said. "While we do not yet know the identities of the attackers or their motives, what we do know is that their cowardly acts will not intimidate the Tunisian people, whose storied heritage is showcased at the site of this attack, the National Bardo Museum."
The museum is a popular tourist attraction, which is near the Tunisian parliament that was in session during the time of the attack.
Tunisia's President Beji Caid Essebsi condemned the attack.
"These monstrous minorities do not frighten us," he said on national TV. "We will resist them until the deepest end without mercy. Democracy will win and it will survive."
By Andrew V. Pestano
