At least eighteen?people have died following the weekend unrest in the city of?Kashi (or Kashgar) in northwest China's Xinjiang Uygur Autonomous Region.

On Sunday, a group of armed terrorists broke into a restaurant in the city center of Kashi at about 4 p.m., killing the restaurant owner and a waiter and setting fire on the restaurant, the regional publicity department said in a statement.

They then ran out of the restaurant and hacked civilians arbitrarily, leaving four dead and 12 injured, while police and fire fighters were striving to put out the fire, it said.

Police then opened fire and shot dead four suspects at the scene, while another suspect died later in hospital, according to the statement.

The statement said it was a "premeditated terrorist attack."

The incident happened after at least seven people were killed by rioters on Saturday night in the same city.

On Saturday night, two rioters hijacked a truck after stabbing dead the driver, and then rammed the vehicle into a crowd in a food market and attacked the pedestrians at random with knives.

At least six people were killed on the spotand 28 others were injured. One of the rioters died while fighting with locals, and the other was apprehended.

The assailant hijacked the truck at 11:45 p.m. Saturday night, according to Tianshannet.com, a local government-run website.

Before the attack, two explosions were also heard. The first occurred at about 10:30 p.m. from a minivan, while the other was heard almost at the same time when the hijack took place.

Xinjiang, home to China's Uygur minority and other ethnic groups, has been under terrorist threat.

Police shot 14 rioters who attacked a police station and killed four people in Xinjiang's Hotan city on July 18.

The attack left four people dead, including an armed police officer, a security guard, a woman and a teenage girl. At least four others were injured.

Police concluded later that the riot was "a severely violent terrorism case" that was organized by terrorism groups.

A big riot happened on July 5, 2009, when rock-flinging and knife-wielding rioters looted shops, torched vehicles and killed nearly 200 people.

In March 2008, five months before the Beijing Olympics, police arrested a 19-year-old Uygur for her foiled terrorist attempt on a passenger flight.