Many people quickly evacuated their homes when the alarms sounded, while a woman died in Mexico City after falling down some stairs.
A strong earthquake has jolted Mexico, leaving one person dead, with people rushing out into the streets of the capital in the middle of the night, days after another powerful tremor.
A woman died in Mexico City after falling down some stairs and hitting her head when Thursday's quake triggered early warning alarms, authorities said.
The epicentre of the 6.9-magnitude quake was near the Pacific coast, 84 kilometres (52 miles) south of Coalcoman in the western state of Michoacan, the national seismological agency reported.
The US Geological Survey (USGS) estimated the magnitude at 6.8.
Michoacan was hit by a powerful magnitude 7.7 earthquake on Monday that left two people dead, damaged several thousand buildings and sparked panic more than 400 kilometres away in Mexico City.
The latest quake again triggered alarms in the capital shortly after 1:00 am (0600 GMT) and caused buildings to shake and sway.
"We had a 6.9 magnitude aftershock with an epicentre in Coalcoman," President Andres Manuel Lopez Obrador said on Twitter.
"It was felt in Michoacan (and the other states of) Colima, Jalisco, Guerrero and Mexico City. So far there are no reports of damage," he added.
'Ring of Fire'
Mexico City Mayor Claudia Sheinbaum said official helicopters had flown over the city and that there were no initial reports of destruction.
"So far there is no damage in the city after the earthquake," she tweeted.
The quake hit at a depth of 12 kilometres, according to the national seismological agency, while USGS estimated the depth at 24 kilometres, located about 410 kilometres from Mexico City.
Monday's tremor came less than an hour after millions of people in Mexico City participated in emergency drills on the anniversary of two deadly earthquakes in 1985 and 2017.
The timing of Monday's tremor was no more than a coincidence, the national seismological agency said. "There is no scientific reason to explain it," it added.
On September 19, 1985, an 8.1-magnitude quake killed more than 10,000 people and destroyed hundreds of buildings. On the anniversary of that earthquake in 2017, a magnitude 7.1 quake left around 370 people dead, mainly in the capital.
During Monday's earthquake, a man was killed by falling debris in a shopping centre in Manzanillo in the western state of Colima. A woman later died of injuries caused by a falling wall in the same city.
Mexico sits in the world's most seismically and volcanically active zone, known as the Ring of Fire, where the Pacific plate meets surrounding tectonic plates.
Mexico City has an early warning alarm system using seismic monitors that aims to give residents enough time to evacuate buildings when earthquakes hit seismic zones near the Pacific coast.