ROME (CNN) -- The metro system and some schools in Italy's capital, Rome, were being evacuated Wednesday following a series of powerful earthquakes that struck the heart of the country.
An initial 5.3-magnitude quake hit central Italy 7 kilometers (4.3 miles) west-northwest of Amatrice, a town devastated by powerful temblors last year, the US Geological Survey (USGS) reported.
While the epicenter was 90 kilometers northeast of Rome, the quake was felt strongly in the capital, sending people running from buildings in a panic.
It struck at 10:25 am (4:25 am ET) at a shallow depth of 10 kilometers and has been followed by eight aftershocks in the same area, including one as strong as 5.7, the USGS reported.
There are no immediate reports of casualties or damage but firefighters told CNN that heavy snow blocking roads has hampered their initial assessment.
Around 850 firefighters are engaged but there have been no requests for rescues so far, the Italian Fire Department said in a Twitter post.
Disaster authorities in Rome said they had been inundated with hundreds of calls from the city.
Officials have begun looking for cracks and damage to structures in the city, many of them ancient and vulnerable from previous tremors.
Amatrice mayor: 'I have no words'
All the aftershocks have all hit around Amatrice, in the mountainous regions of Marche, Lazio and Abruzzo.
Nearly 300 people died in central Italy in quakes around Amatrice in August, and the town center, once popular with tourists, was reduced to rubble.
Another series of quakes hit the region in October, but the impact was small as most people had evacuated from the previous tremors.
"I don't know if we did something bad. That's what I have been asking since yesterday," Amatrice Mayor Sergio Pirozzi told the AFP news agency.
"We have got up to two meters of snow and now another earthquake. What can I say? I have no words."
Italy lies atop the convergence of the African and Eurasian tectonic plates, making it the most quake-exposed country in the Mediterranean.
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