Video from the scene showed at least two cars at a 45-degree angle, sitting atop crushed cars below.
It was not immediately clear if there were any injuries or deaths.
Mexico City mayor Claudia Sheinbaum said on Twitter that she was headed to the scene, which she indicated was on line 12.
🚨Actualización del accidente en línea 12 del metro, CDMX 🚨.
➡️ Cerradas las vialidades cerca del metro Olivos.
➡️ Aún no hay reporte oficial de número y nombre lesionados, calculan 50. pic.twitter.com/dz0A2izlCx
— SUUMA Voluntarios 🚑 (@SUUMA_CDMX) May 4, 2021
This is a breaking news story. Check back for updates.