A group of protesters in Mexico City drove a pickup truck through the door of the country's presidential palace.
They were met by police officers who used tear gas on the demonstrators.
The group was protesting the 2014 mass disappearance of a group of 43 Mexican students. A committee set up to investigate the case was later described as a “state crime”.
President Andrés Manuel López Obrador was inside the building at the time and was holding a daily press conference.
“The door will be locked and there will be no problem,” he said, adding that the demonstrators would meet with members of his government.
In 2014, 43 students were returning from Iguala to Ayotzinapa after attending a protest against what they saw as discriminatory practices in teacher hiring. They were confronted by the municipal police, who opened fire on the buses they were traveling in.
Officers maintain they did so because the buses had been hijacked, while the surviving students say the drivers agreed to give them a ride.
Three students were killed, two of them shot dead, while the third's mutilated body was found the next morning near the scene of the shooting.