A suspect arrested on Friday after a stolen truck barreled into pedestrians on a busy Stockholm street -- leaving at least four people dead -- is being held of suspicion of perpetrating a terror attack, a government official has said. The man in custody, whose appearance matches the description of a person of interest, is being held on "suspicion of terrorist crimes through murder," Karin Rosander, spokeswoman for Sweden's prosecutor's office, told CNN via email early Saturday.