forward attack();
public attack()
{
    new Float:min_dist,
        Float:curr_dist;

    for (new npcid = 0; npcid < sizeof(npc); npcid++) {
        GetNPCPos(npc[npcid][npc_ID], ftmp[0], ftmp[1], ftmp[2]);
        npc[npcid][npc_TargetID] = -1;
        min_dist = 99999.0;

        // get closest player
        for (new playerid = 0; playerid < maxplayers; playerid++) {
            if (!IsPlayerConnected(playerid) || IsPlayerNPC(playerid)) {
                continue;
            }

            curr_dist = GetPlayerDistanceFromPoint(playerid, ftmp[0], ftmp[1], ftmp[2]);
            if (min_dist > curr_dist && curr_dist < npc[npcid][npc_TargetDist]) {
                min_dist = curr_dist;
                npc[npcid][npc_TargetID] = playerid;
            }
        }

        // shoot in closest player
        if (npc[npcid][npc_TargetID] != -1) {
            pNPC_ShootAt(npc[npcid][npc_ID], npc[npcid][npc_TargetID]);
        } else {
            StopNPC(npc[npcid][npc_ID]);
        }
    }
    return 1;
}