One U.S. citizen was killed in the van attack in Las Ramblas, Barcelona, that left a total of 14 dead and dozens wounded, the U.S. State Department confirms to CBS News.
Another U.S. citizen suffered minor injuries in the attack, officials said.
The victims -- both deceased and wounded -- were from at least 34 different countries, including France, Germany, China, Australia and Peru, Spanish emergency services announced Friday.
Secretary of State Rex Tillerson said in a news conference Friday that officials were "still confirming the injuries and deaths of others."
"We express our deepest sympathies to the loved ones of this individual, and obviously the others who have suffered loss of life. We offer our thoughts and prayers to their families as they're going to be dealing with a very few tough days ahead of them," Tillerson said.
An Australian family said a 7-year-old boy was missing after he was separated from his mother, who was seriously injured in the attack.
Authorities investigating both attacks believe there may have been a cell of eight people involved, and that the group planned to use butane gas canisters, the Reuters news agency reports, citing an unnamed judicial source.
U.S. law enforcement officials told CBS News there is intelligence that indicates the Barcelona attack was more than just an ISIS-inspired attack.
CBS News national security analyst Fran Townsend said the attack looks like it was "much more directly controlled than merely inspired."
"As you look at the chronology, this was a fairly large cell, had to have been in place for a while -- pretty good planning," Townsend said on "CBS This Morning."
"You had the house that blew up when they failed to put together these gas canisters -- probably for a car bomb," Townsend explained. "Then you had the tragic sort of seven-block rage of this car killing 14. You also had in Cambrils last night another car attack."