As an attack in Barcelona, Spain, today left 13 people dead and injured more than 50, U.S. Secretary of State Rex Tillerson offered condolences for the "loss of life and injuries" of "so many innocent people, yet again."
In the incident local police called a "terror attack," a van slammed into pedestrians near Catalunya Square in Barcelona's Las Ramblas district, a busy tourist area.
One man is in custody, police said.
Tillerson said this incident has "the hallmarks, it appears, of yet another terrorist attack."
To terrorists around the world, Tillerson said, we are "resolved to find you and bring you to justice."
Tillerson added that the U.S. stands ready to assist authorities in Barcelona.
President Donald Trump condemned the attack in a tweet, encouraging Spain to "be tough and strong" and saying the U.S. "will do whatever is necessary to help."
First lady Melania Trump also offered her condolences, tweeting, "Thoughts and prayers to #Barcelona".
The athletic department at Clemson University in South Carolina wrote on Twitter that its men's basketball program is in Barcelona, but the entire travel party is "safe and secure" and is expected to return to Clemson on Friday.
"Our thoughts are with the people of Barcelona and those injured at this time," the Clemson athletic department added.
ABC News' Erin Dooley and Meghan Keneally contributed to this report.