Aftershocks were still being felt on Tuesday, state media said, a day after the United States Geological Survey (USGS) said a 6.6-magnitude quake shook the region southwest of Sichuan’s capital Chengdu around 1 p.m. Monday.

So far 248 injuries have been reported and at least 12 people remain missing, according to state media.

Images showed rescue workers carrying injured residents over makeshift bridges in Luding County, near the quake’s epicenter.

The USGS said quake’s epicenter was about 43 kilometers (27 miles) southeast of Kangding, a city of around 100,000 people. Over a million residents in surrounding areas are estimated to have experienced moderate tremors in the aftermath of the quake, it added.

Some homes were severely damaged in the quake, with images appearing to show whole buildings had collapsed into piles of bricks and wooden beams.

China activated a Level 3 emergency response and dispatched rescue workers to Luding County on Monday, according to China’s State Council. Chinese broadcaster CGTN said rescue workers were helping to clear roads blocked by landslides triggered by the quake.

Sichuan, a province of 84 million people, was already facing a very challenging summer before the powerful quake. In the last two months, the province has endured drought and its worst heatwaves in 60 years.

The landlocked area is prone to earthquakes because of the Langmenshan Fault which runs through Sichuan’s mountains.

A 7.9-magnitude earthquake that struck Sichuan in 2008 was one of the country’s most devastating. Almost 90,000 people were killed and tremors were felt in cities more than 1,450 kilometers (900 miles) away.

Last year, a 6.0-magnitude earthquake struck Sichuan, killing three people and injuring 60, according to state media at the time.

CNN’s Hannah Ritchie contributed reporting.