Two men drove a truck right into a group of jogging policemen and then, armed with knives and grenades, started an assault on their barracks Monday, in a tense Chinese province bordering Central Asia. The assault on the military police unit occurred in Kashgar, Xinjiang province, where the majority are Muslim, and resulted in 16 dead border patrol officers and 16 others wounded, according to Chinese state media.

Just four days away from the start of the Olympic Games in Beijing, the assault pointed out the weak spots of the Chinese authorities as they try to safeguard the capital for the hundreds of thousands of foreign athletes, journalists and visitors who have already started to arrive here.

Officials qualified the incident as an act of terrorism and implied the criminals were associated with an obscure dissident movement that is seeking independence for China’s Uighur minority, a Turkish-speaking people who dominate Xinjiang Province.

The violent event in Kashgar — an oasis city about 2,000 miles away from Beijing — is the deadliest outbreak of violence since the early 1990s, when officials began to trace anti-Chinese activity in the immense desert that extends into Central Asia and communicates with seven countries, including Afghanistan and Pakistan.

The attack in Kashgar happened just before sunrise as a brigade of border patrol police was jogging outside their barracks in the city center. According to official media accounts, two men driving trucks crashed their vehicles into the soldiers, killing or injuring ten.

The attackers then rushed out of the trucks armed knives and slashed and stabbed the soldiers. They also tossed two grenades at the barracks “causing explosion,” the account said. The police apprehended the attackers, one of whom suffered a leg injury, but did not release their names.

In Beijing, the authorities have strengthened the capital with soldiers, missile launchers and sidewalk cameras, and they said they were confident the Games would take place without incident.

“We are prepared to deal with any kind of security threat and we are confident we will have a safe and peaceful Olympic games,” said Sun Weide, a Beijing Organizing Committee representative.

In spite of the capital’s omnipresent security, a minor group of dislocated residents put on a brief demonstration near Tiananmen Square on Monday afternoon to protest the lack of compensation they were given to make way for a redevelopment project. The protest, which attracted a crowd of police and caused a traffic jam, was immediately dissolved.

In current years, China has carried on an increasingly muscular fight against those it describes as Muslim separatists. The East Turkistan Islamic Movement, a group qualified as a terrorist organization by the United States and China, is often blamed for much of the brutality in Xinjiang.

However, according to human rights defenders, the official reports are amplified to justify wide-ranging repressions on Uighur advocates.