The United States condemns Wednesday's attack at Tunisia's national museum, US Secretary of State John Kerry said in a statement.
"The United States stands with the Tunisian people at this difficult time and continues to support the Tunisian government's efforts to advance a secure, prosperous, and democratic Tunisia," he said.
Gunmen stormed the museum earlier on Wednesday, killing two Tunisians and 17 foreign tourists.
"The United States condemns in the strongest possible terms today's deadly terrorist attack at the National Bardo Museum in Tunis, where gunmen killed 19 people and wounded more than 20 others," he said.
"We extend our heartfelt sympathy to the victims' families and loved ones."