Homeland Security Secretary Janet Napolitano warned Thursday that a major cyber attack – the “cyber 9/11” – is a looming threat and could have the same sort of impact as last year’s Superstorm Sandy, which knocked out electricity in much of the Northeast, according to an article from Reuters.

Napolitano said such an event could happen “imminently” and that critical infrastructure – including water, electricity and gas – was vulnerable, the article says.