Mexico's President says 22 people have died at a school that collapsed in the nation's capital due to Tuesday's 7.1 magnitude earthquake.

President Enrique Pena Nieto said that two of the bodies found were adults.

It is not clear whether the deaths are already included in the overall toll of at least 149 across the country.

​Pena Nieto visited the school late on Tuesday and said in comments broadcast online by Financiero TV that 30 children and eight adults were still reported missing.

Rescue workers were continuing to search and listening for sounds from the rubble.

Earlier the head of Mexico's civil defence agency said the nationwide death toll from Tuesday's earthquake has risen to 149.

Luis Felipe Puente said 55 people died in Morelos state, just south of the capital, while 49 died in Mexico City and 32 died in Puebla state, the location of the earthquake's epicentre.

Ten people died in Mexico State, which surrounds the capital, and three in Guerrero state. The count did not include one death reported by officials in Oaxaca state.

The US Geological Survey (USGS) said the magnitude 7.1 quake was centered near the Puebla state town of Raboso, about 76 miles southeast of Mexico City.

UN Secretary-General Antonio Guterres said he is saddened by the loss of life and damage resulting from the earthquake.

Mexico City earthquake in pictures Show all 13 1 /13 Mexico City earthquake in pictures Mexico City earthquake in pictures A handout picture provided by the citizen Edgar Cabalceta shows a general view of Mexico City following a magnitude 7.1 earthquake, in Mexico City, Mexico EPA Mexico City earthquake in pictures Rescuers and residents look for victims amid the ruins of a building knocked down by a magnitude 7.1 earthquake that jolted central Mexico damaging buildings, knocking out power and causing alarm throughout the capital on September 19, 2017 in Mexico City, Mexico. The earthquake comes 32 years after a magnitude-8.0 earthquake hit on September 19, 1985 Getty Images Mexico City earthquake in pictures A police officer stands guard near a building which collapsed after a quake rattled Mexico City RONALDO SCHEMIDT/AFP/Getty Images Mexico City earthquake in pictures Rescuers, firefighters, policemen, soldiers and volunteers remove rubble and debris from a flattened building in search of survivors after a powerful quake in Mexico City AFP/Getty Images Mexico City earthquake in pictures Rescuers and residents look for victims amid the ruins of a building knocked down by a magnitude 7.1 earthquake that jolted central Mexico damaging buildings, knocking out power and causing alarm throughout the capital on September 19, 2017 in Mexico City Getty Images Mexico City earthquake in pictures People try to rescue survivors from a collapsed buildings after a magnitude 7.1 earthquake on the Richter scale in Mexico City, Mexico, 19 September 2017. At least 79 people lost their lives in the states of Morelos, Puebla and Mexico by the earthquake of magnitude 7.1 on the Richter scale. EPA Mexico City earthquake in pictures People clear rubble after an earthquake hit Mexico City, Mexico REUTERS Mexico City earthquake in pictures People clear rubble after an earthquake hit Mexico City, Mexico REUTERS Mexico City earthquake in pictures Rescuers and residents assists an injured victim amid the ruins of a building knocked down by a magnitude 7.1 earthquake that jolted central Mexico damaging buildings, knocking out power and causing alarm throughout the capital on September 19, 2017 in Mexico City, Mexico. The earthquake comes 32 years after a magnitude-8.0 earthquake hit on September 19, 1985. Getty Images Mexico City earthquake in pictures People remove debris outside a collapsed building after an earthquake in Mexico City, Mexico REUTERS Mexico City earthquake in pictures People remove debris as they search for possible victims after a quake rattled Mexico City on September 19, 2017. A powerful earthquake shook Mexico City on Tuesday, causing panic among the megalopolis' 20 million inhabitants on the 32nd anniversary of a devastating 1985 quake. The US Geological Survey put the quake's magnitude at 7.1 while Mexico's Seismological Institute said it measured 6.8 on its scale. The institute said the quake's epicenter was seven kilometers west of Chiautla de Tapia, in the neighboring state of Puebla. AFP/Getty Images Mexico City earthquake in pictures A security guard walks over debris of a building which collapsed during a quake in Mexico City AFP/Getty Mexico City earthquake in pictures Reconstruction work in the towns affected by the telic movement has begun. Several temples suffered severe damage. Rex

Mr Guterres extended his condolences to the government and people of Mexico and wished those injured a speedy recovery, according to a statement released by his spokesman.

The statement said the UN stands ready to assist Mexico following the quake.