Across Mexico on Wednesday, tens of thousands of people took to the streets in a number of cities, demanding the safe return of 43 students who went missing last week.

They came to show their support for the students who went missing last week after state police shot into a crowd of protesters in Iguala, Guerrero, killing eight people. Three of them were students.

A heavy presence of federal police has been deployed around Iguala, where a mass grave was uncovered containing the burned bodies of 28 victims.

Authorities are investigating a local criminal group called Guerreros Unidos, whose members include rogue police, to determine if they might be behind the crimes. Twenty-nine people, including 22 police officers, have been charged so far.

Mexican students participating in Wednesday’s marches vow to go on a national strike on Thursday, saying they will continue until they receive confirmation that their fellow students are found.

CCTV America’s Franc Contreras reports.