An online attack against dozens of law enforcement agencies has left some officials wondering whether they'll be able to ward off future hacking attempts. The Missouri Sheriff's Association says the hackers stole hundreds of police academy training files, the names of people who provided anonymous crime tips to police, jail inmates databases, and arrest warrants. The group, only known as "anonymous", also hacked into several other law enforcement agency's sites in Missouri and Arkansas. Many sites were hosted by the same company. The hackers posted some of the stolen information online, including emails, credit card numbers and public crime tips. Internet security experts say the best hackers can beat the tools meant to stop them and many potential victims don't suspect they'll be targeted.