While playing the game, your hood will undergo attacks from other factions.
To save yourself some time and end these disaster quickly, simply jack any vehice in which you can access extra missions using R3 (i.e., police vehicles, fire vehicles, taxicabs, ambulance, et al.).
Enter L2, RIGHT, L1, UP, X, L1, L2, R2, R1, L1, L1, L1.
During gameplay enter TRIANGLE, R1, R1, LEFT, R1, L1, R2, L1.
Get into the water then swim back out and a message will appear claiming that the hood is yours.