KASHGAR, China — Soldiers patrolled the streets Tuesday where bomb-tossing attackers killed 16 police in China's western Xinjiang region, prompting a full security alert in the restive Muslim territory just days before the Olympic Games.

Police boarded vehicles and searched passengers' bags on the roads leading into Kashgar, the city near the Afghan-Pakistan border where Monday's attack happened. Government offices, schools and hospitals were also to be under greater watch, the official Xinhua News Agency reported.

Sixteen officers were killed and another 16 injured Monday in the audacious attack in which two assailants rammed a group of police with a dump truck during their morning jog and hurled explosives at them.

Kashgar's Communist Party secretary, Shi Dagang, called the attack an act of premeditated terrorism and told reporters that the two attackers prepared written statements beforehand saying "they had to wage 'holy war,"' Xinhua reported.

China's Olympic organizers immediately said security precautions were ready to ensure safety in Beijing and other Olympic venues when the games open Friday.

China has made safety a priority for the Olympics, mobilizing hundreds of thousands of police, military and local residents as part of a huge security net over the capital. But the Xinjiang attack underscored that with so much security focused on Beijing, areas far from the capital make tempting targets.

The timing so close to opening day heightened the attack's shock value.

"Security for the Olympic Games is of paramount importance. The more we give, the safer and more secure the residents will feel," Xinhua quoted Han Shubin, the deputy director of an Urumqi police division, as saying.

The two attackers arrested on the scene were Uighurs, a mainly Muslim ethnic minority group, some of whom have waged a sporadically violent rebellion against Chinese rule.

Li Li, a spokesman for Xijiang Public Security Bureau, said 18 terrorist suspects had been arrested in the region this year. The two men arrested in Monday's attack were not among that number, Li said.

Last month, officials said China detained 82 suspected terrorists in Xinjiang in the first half of the year for allegedly plotting attacks against the Olympics.

Under Chinese law, suspects are not officially considered arrested until they have been charged with a crime, so it was unclear whether the 18 were among the 82 detained.

In a videotape last month, an extremist Uighur group believed to be based across the mountainous border in Pakistan's tribal frontier threatened to target the Olympics.

State broadcaster China Central Television said in its noon broadcast Tuesday that the two men, aged 28 and 33, had planned the attack, stealing the dump truck and ramming it into some 70 border patrol paramilitary police as they passed a hotel during a morning jog. They then hurled the explosives and attacked the policemen with knives.

One of the attackers lost a hand when the homemade explosives blew up. Afterward, police recovered additional explosives, a gun, and "propaganda materials about a holy war," state media said.

On Tuesday, the streets in northwestern Kashgar appeared quiet, though four soldiers in uniform and helmets were seen marching up the sidewalk on patrol, carrying short black clubs.

"I heard the attack yesterday morning. It was not loud. It just sounded like a car's tire bursting," said a waitress who worked in a small nearby restaurant who refused to give her name for fear of reprisals.

"It doesn't seem like there are more police on the streets, but the neighborhood patrols seem to be tighter. They're coming around and checking more often," she said.

The assault took place on a tree-lined thoroughfare in front of the small Yiquan Hotel, housed in an older three-story building covered in dusty white, yellow and maroon tile.

The hotel was closed Tuesday, with a large plastic tarp covering the entrance. Just to the right of the hotel, a group of four trees appeared to have been recently uprooted.

Underscoring tensions in the region, Chinese authorities clashed late Monday with two Japanese journalists who rushed to Kashgar to report on the attack, then later apologized to the newsmen after Tokyo said it would lodge a formal complaint, Xinhua and Japanese officials said.

The clash occurred when the journalists tried to enter a restricted area, Xinhua said. Japan's Chief Cabinet Secretary Nobutaka Machimura told reporters in Tokyo that the two had been detained and roughed up adding: "We plan to lodge a strong protest."

Xinhua cited Eskar, an official from the regional office of foreign affairs in Kashgar, as saying local authorities apologized to the reporter and photographer, though they had disobeyed the rules.

"We are sorry for the incident and the damage to the equipment that belonged to the reporters," Eskar, who was identified by just one name, was quoted as saying. He said the border police would pay to repair the equipment and "the medical bills for physical checks" of the journalists, Xinhua said.

Monday's attack was all the more surprising because it follows years of intensive security measures in Xinjiang. A wave of violence in the 1990s mainly targeted police, officials and Uighurs seen as collaborators. Also in the 1990s, separatists also staged nearly simultaneous explosions on three public buses in the provincial capital of Urumqi.

In response, the government stationed more paramilitary units in the region and shut unregistered mosques and religious schools seen as hotbeds of anti-government extremism.