MEXICO CITY — "Enough, I'm tired," Mexico's attorney general, Jesús Murillo Karam, said at the end of a grisly hour-long news conference Friday during which he explained how 43 missing students from Guerrero state were probably shot, burned and dumped in a river by drug gangsters working in cahoots with corrupt police.

The offhand remark has morphed into an Internet hashtag — #yamecanse (the Spanish version) — and a rallying slogan for the anger and frustration that has yet to subside in Mexico. On Saturday night, protesters marched on the attorney general's office and the national palace in the capital's main Zocalo plaza. They sprayed graffiti and set fire to the palace's wooden door, a blaze captured in photos spreading across the Internet on Sunday morning.

Protesters set fire to the door of the Mexican president's ceremonial palace in Mexico City as they denounce the apparent massacre of 43 students in the state of Guerrero in September. (Edgard Garrido/Reuters)

The September disappearance of 43 teachers' college students from Guerrero has sparked outrage in Mexico. Many people, including parents of the victims, have failed to be convinced by the government's explanations and are demanding more evidence about the students' apparent deaths. Murillo Karam did not assert that the government had positively identified the remains of the students. He said investigators were still trying to match DNA.

On Twitter, one poster, Uri Sanchez-Molina, wrote: "The land of my ancestors and the mountains & hills of my grandparents dotted with people disappeared & forgotten by the state. #YaMeCanse."