A damaged car is seen outside a building after an earthquake in Mexico City, Mexico, Sept 19, 2017.[Photo/Agencies]

MEXICO CITY - A magnitude 7.1 earthquake stunned central Mexico on Tuesday, killing at least 138 people as buildings collapsed in plumes of dust. Thousands fled into the streets in panic, and many stayed to help rescue those trapped.

Scores of buildings collapsed into mounds of rubble or were severely damaged in densely populated parts of Mexico City and nearby states. Mayor Miguel Angel Mancera said buildings collapsed at 44 places in the capital alone.

The quake is the deadliest in Mexico since a 1985 quake on the same date killed thousands. It came less than two weeks after another powerful quake left 90 dead in the country's south.

Mancera said at least 30 had died in Mexico City, and officials in Morelos, just to the south, said 54 had died there.

At least 26 others died in Puebla state, according to state disaster prevention chief Carlos Valdes.

Gov. Alfredo del Mazo said at least nine had died in the State of Mexico, which also borders the capital.

Mancera said that 50 to 60 people were rescued alive by citizens and emergency workers.

The US Geological Survey said the magnitude 7.1 hit at 1:14 pm (2:15 pm EDT) and it was centered near the Puebla state town of Raboso, about 76 miles (123 kilometers) southeast of Mexico City.

The quake caused buildings to sway sickeningly in Mexico City and sent people throughout the city fleeing from homes and offices, and many people remained in the streets for hours, fearful of returning to the structures.

Electricity and cellphone service was interrupted in many areas and traffic was snarled as signal lights went dark.

Mexico City's international airport suspended operations and was checking facilities for any damage.

Alarms blared and traffic stopped around the Angel of Independence monument on the iconic Reforma Avenue.