Triglavians attacked pilots in Perimeter today, destroying their ships and podding them. Haulers were surprised as they lost cargo to the attacks. Groups of Triglavians will spawn around Pochven systems. Since Caldari was the worst of the four empires to defend their systems, their systems constitute a large share of the Pochven systems. This means Triglavian attacks will occur in and around Jita and other Caldari systems.
You can prepare yourself by increasing your standings with Triglavians. Triglavians won’t shoot anyone with positive standings.
Additional information can be found here.