EL ALTO, Bolivia (CBS Newspath) — At least seven university students died and four were injured on Tuesday when they fell from a fourth-floor after a railing broke during a student assembly at the Public University of El Alto, a neighboring city of La Paz, authorities reported.

Three students died instantly and the other four died minutes after being admitted to nearby hospitals.

Police Commander General Jhonny Aguilera said during a press conference that the deceased are four men and three women between the ages of 21 and 23.

In total, 11 students dropped about 16.7 meters, Aguilera said. The remaining four students were admitted into nearby hospitals, three of them in intensive care.

Hundreds of students were holding the assembly and crammed in a narrow corridor when the metal railing broke and several of the students fell.

Video images showed how students were able to pull back to safety one young woman.

The president of Bolivia, Luis Arce, sent a message on social media regretting “the tragedy that occurred at the Public University of El Alto (UPEA), where several people died and were injured. Our deepest condolences to the Alteño people and to the bereaved families. We look forward to the early clarification of the facts.”

Parents are demanding an investigation because the university isn’t having any in-person classes due to safety measures to prevent new infections of COVID-19, but the students were summoned to an assembly.