Three missing Mexican students were found to have been killed last month in the western state of Jalisco after criminals confused them with members of a rival gang, authorities said Monday. Their bodies were dissolved in acid.

They were mistaken for rival gang members and were kidnapped by the Jalisco New Generation Cartel. The students — Salomon Aceves Gastelum, 25; Daniel Diaz, 20; and Marco Avalos, 20 — had gone missing on March 19, after they had been filming a school project at a house used by a rival gang, on the outskirts of the city of Guadalajara. The residence belonged to one of their aunts, involved in a prostitution ring.

"Without knowing it, the students were in a very dangerous place which was being watched by hit men from the New Generation cartel," the prosecutor's office said.

Read more: Mexican journalist gunned down in violent Veracruz state 

Guillermo del Toro: 'terrifying, madness' 

The students' gruesome fate horrified Mexico, triggering vehement protests on Monday night.

"Words can't describe the dimension of this madness," Oscar-winning Mexican director Guillermo del Toro wrote on Twitter. "Three students are killed and dissolved in acid. The 'why' is unthinkable, the 'how' is terrifying."

Actor Gael Garcia Bernal wrote on Twitter "What sadness. This nightmare has to stop."

"The effects of crime and violence against any person is bad enough, but it is worse when it is a case of young people who have a future, who are studying, who are working for Mexico," said Luis Gonzalez Perez, president of the country's National Human Rights Commission.

Under the hashtag #NoSomosTresSomosTodxs (It's not three, it's all of us), illustrators also reacted to the events:

Mexico's efforts to rein in brutal violence linked to drug trafficking are not convincing. There are currently more than 33,000 people missing in the country. Cases of missing people often go unsolved, and more than 90 percent of violent crimes are never punished.

Read more:  Narco cartels target politicians as Mexico's elections near

eg/als (AP, Reuters, dpa, AFP)