Mafia Massacre is a side mission in Grand Theft Auto III.
This side mission involves guiding an explosives-rigged RC Bandit around Saint Mark's in an attempt to destroy gang cars, in this case, Mafia Sentinels, in an allotted amount of time. To start the mission you must enter a TOYZ van which is located in Saint Marks across from Momma's Restaurante. You can activate the bomb by using the fire button, or by driving into the wheels of the target car.
During the mission, you are exempt from police attention, so you can also kill bystanders, including cops without gaining a wanted level. However, any wanted level you had prior to starting the mission is reinstated, so it's best not to start this one with four stars or more; the van also isn't the best getaway car.