Trump denounces Barcelona terror attack in tweet

The president added that the U.S. "will do whatever is necessary to help."

"The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help. Be tough & strong, we love you!" wrote Trump on Twitter Thursday afternoon.

A van drove into pedestrians on a boulevard and public square popular with tourists in Barcelona earlier in the day, leaving at least 13 people dead and more than 80 others injured — which law enforcement in the city labeled an act of terrorism.

From Panama, where he was traveling Thursday, Vice President Mike Pence expressed that "the latest scenes of carnage and and mayhem sicken us all."

"Whatever inspired today's terror attack, the United States stands ready to assist the people of Spain and find and punish those responsible," said Pence.

"Terrorists around the world should know the United States and our allies are resolved to find you and bring you to justice," said Tillerson.