At least 31 people were killed and more than 90 injured in an attack yesterday on a street market in Xinjiang.
Two off-road vehicles ploughed into people in the regional capital, Urumqi, and unidentified assailants threw explosives, Xinhua reported. The cars then crashed head-on and one exploded. The authorities did not identify the suspects.
Watch: Dozens dead and scores injured in Xinjiang 'terrorist' attack
It was not clear who was behind the violence, but the authorities have blamed a series of attacks in public places in recent weeks on Muslim ethnic-Uygur separatists from Xinjiang.
Yesterday's incident in North Gongyuan Street was the bloodiest single act of violence in the restive northwestern region since about 200 people were killed in clashes in Urumqi in 2009 between Uygurs and ethnic Han Chinese.
The Ministry of Public Security described it as a "serious violent terrorist incident". And President Xi Jinping called for those behind the incident to be severely punished.
The injured were sent to hospitals for treatment and the scene was sealed off for several hours. Photographs posted on social media showed injured people on the ground, with clothes and other items strewn across the street.
Fan Fangfang, who owns a small supermarket in North Gongyuan Street near the scene of the blasts, said that she had been woken by loud bangs.
"I heard at least six or seven explosions. It sounded horrible," she said. "I didn't dare to go out to have a look."
Fan said the makeshift market's customers and vendors were mainly Han Chinese and that more than 100 sellers set up their stalls in an 800-metre-long section of the street.
"The people who come here are innocent ordinary people: housewives, retired people and hard-working market sellers. Why and who would attack us in this way?" she said.
"Where can I go to be safe in the city in the future? Nowhere will be safe. I feel very worried."
A number of crowded public places have been targeted on the mainland in recent months.
A bomb and knife attack at the end of last month at the main railway station in Urumqi killed one bystander and wounded 79 people. Two attackers also died.
Security in the city has been tightened since the attack, which happened as Xi was ending a visit to the region.
Twenty-nine people were stabbed to death at a train station in Kunming in March.
In October, a car burst into flames in Tiananmen Square in Beijing, killing five people, in what the government said was a terrorist attack.
Tensions between Han Chinese and Uygurs in Xinjiang have been simmering for years. Human rights organisations and Uygur exiles say curbs on their language, culture and religion have created anger, a claim that Beijing rejects.