The FBI has begun preparing for a major mole hunt to determine how anti-secrecy group WikiLeaks got an alleged arsenal of hacking tools the CIA has used to spy on espionage targets, according to people familiar with the matter.

The leak rattled government and technology industry officials, who spent Tuesday scrambling to determine the accuracy and scope of the thousands of documents released by the group. They were also trying to assess the damage the revelations may cause, and what damage may come from future releases promised by WikiLeaks, these people said.

It was all a familiar scenario for a government that has repeatedly seen sensitive information compromised in recent years.

In the wake of revelations from Army private Chelsea Manning and former National Security Agency contractor Edward Snowden, officials sought to tighten security procedures, and federal agents came under greater pressure to find and prevent secrets from spilling out of the government.