2011
City employees in Atlanta coming to work Friday morning were told not to turn on their computers and WiFi at the Atlanta airport was turned off due to a ransomware attack that hit municipal systems on Thursday .
 ( ransom: a ransomware attack,  their computers: victim, Friday morning: time, Atlanta: place, City employees: victim, Atlanta airport: victim) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( ransom: a ransomware attack,  their computers: victim, Friday morning: time, Atlanta: place, City employees: victim, Atlanta airport: victim) 