Terrorists use violence in pursuit of political goals. While terror often has severe consequences for victims, it remains an open question how terror attacks affect the general population. We study the behavioral response of citizens of cities affected by 7 different terror attacks. We compare real-time mobile communication patterns in the first 24 hours following a terror attack to the corresponding patterns on days with no terror attack. We find that the difference between male and female communication patterns are amplified following a terror attack. Knowledge about citizens’ behavior response patterns following terror attacks may have important implications for the public response during and after an attack.