My friend got robbed last night

So last night I was asleep and got a call from another friend saying that our friend got robbed at gunpoint and they took everything, his car, wallet, phone. The police are investigating atm but I just can’t help but feel like I need to do something on my own. I need to find the mfks who did it and do something back. They legit ruined bros life and I can’t let that shit slide. I don’t know who they are and where they stay at but it should be in the area. What should I do.