There is chaos in Los Santos. Sweet is on the phone trying to lock down Grove Street when you enter to help. Cesar soon enters the house and asks CJ to help get his house back and get 3 of his gangster at the Unity Station.
CJ and Cesar (and your gangsters if you recruited some) then have to go to meet Cesar's gangsters and attack the Vagos in house.
Once you've taken the house back, go to the other side and take down more Vagos, this time with the assistance of one of Cesar's gangsters with an RPG. After that, you have go kill more Vagos in another area. Watch out for the two Vagos with a flame thrower and an RPG. Kill the last group of Vagos and the mission is complete.
Note: If Cesar dies, the mission is failed.
Best to get some body armour and a good gun before going and recruit some of your gang members too.
After you kill everyone at the front of the Vagos house, go through and ambush the rest from behind by going through a building.
When you attack the second wave of Vagos, make sure the Vagos don’t come too close or Cesar’s gangster will blast his RPG at Cesar and kill him.