The Attempted Assassination of Mayor Garcia happens after the death of Gillian B. Loeb, a memorial was made in his honor the day after his death at the hands of the Joker. However during the funeral, it is interrupted by the Joker.
When Gordon and Batman arrived at the apartment where Patrick Harvey and Richard Dent's bodies were discovered, they found out from a newspaper picture of the mayor (drawn with the Joker's face) that he was going to be the Joker's next target.
While the funeral was being held in honor of Commissioner Loeb, Bruce Wayne went to Melvin White's apartment to find the Joker, but discovered the Gotham City Honor Guards tied up and blindfolded. Bruce took off the tape of one of the hostages and listened to the man's story: the Joker and his thugs took their clothes and tied them up in the apartment. During the funeral, when the guns are being set off, the Joker appears, without make up, and in disguise, and attempts to kill the mayor, but Gordon gets in the way of the shot at the last moment and is presumed dead for a while. The Joker, however, escapes.
Harvey Dent finds Thomas Schiff and realises by his name tag that says "OFFICER RACHEL DAWES", that Rachel is the Joker's next target and calls Rachel to inform her of Gordon's death and to go to someone she can trust - Bruce. Batman finds Sal Maroni and demands for the Joker's location. He even goes as far as throwing him two stories off a balcony and breaks his legs. Maroni, however, doesn't give in to the Batman's threats because he needs to be afraid of the real monster: the Joker. With everything getting out of hand, Batman tells Harvey to hold a press conference the next day where he will reveal his true identity.