The shallow, 7.1 magnitude quake, which struck Tuesday afternoon local time (Wednesday morning NZT), killed at least 225 people and caused major damage across states in the centre of the country.
The temblor struck at 1:14 pm (1814 GMT) Tuesday, two hours after a simulation exercise was held to commemorate the powerful magnitude-8.1 natural disaster that struck Mexico City exactly 32 years ago (on September 19, 1985) and left thousands dead in the capital.
A day after a vicious quake leveled apartment buildings, damaged hospitals and flattened an elementary school in Mexico, people mobilized on Wednesday for a massive rescue effort, digging in a frantic search for survivors.
In a video message, President Enrique Pena Nieto urged people to be calm and said authorities were moving to provide help as 40 per cent of Mexico City and 60 per cent of nearby Morelos state were without power.
Rescue efforts in Mexico City are focused on 10 collapsed buildings where people may still be alive.
Students of the Mexico City school that collapsed after a powerful natural disaster hit Tuesday afternoon were seen being pulled out of the rubble in dramatic video posted to social media.
The Health Ministry said hospitals have treated 2,633 people injured in the quake, most in the capital, where 1,998 people suffered injuries.
A total of 115 were killed in Mexico City, Mancera confirmed.
Volunteers formed human chains at other sites to remove rubble and in one case to transport a stretcher to rescue workers. They lived on the fifth floor of the collapsed Amsterdam Avenue building. In the confronting footage, dozens of high-rise buildings can be seen toppling to the ground as hundreds of residents run for their lives.