The organisers of the Beijing Olympic Games say they are well placed to handle security, after reports that 16 policemen were killed in a suspected terrorist attack in northwestern China.
Chinese police have arrested two people believed to have been responsible for the bomb and knife attack on a border post in the mainly Muslim province of Xinjiang.
Police said they had information separatists from the East Turkestan Islamic Movement had been planning attacks in the run-up to the Games.
With just four days to the start of the Olympics, a group of about 20 residents staged a protest near Tiananmen Square, saying they had been evicted from their homes to make way for a new shopping development in their area.
Today's attack has raised security fears just four days before the Beijing Olympics.
State media has reported that two men drove a lorry into a border post and threw two grenades.
16 other members of the border patrol division were also wounded.
Two men drove a lorry up to the border station in Kashgar city as a group of officers were carrying out morning fitness exercises, according to Xinhua news agency.
Both attackers were arrested, one of them with a leg injury sustained during the raid, according to Xinhua.
The incident comes after repeated warnings in recent months from the Chinese government that militants from the Xinjiang region were planning to stage attacks to disrupt the Games.
The Beijing Olympic organisers (IOC) said they did not know yet if there was a direct connection to the showpiece sporting event, which begins on Friday.
However, a spokesman for the IOC said he was confident that Olympic participants and spectators would be safe.
'China has focused on strengthening security and protection around Olympic venues and at the Olympics Village, so Beijing is already prepared to respond to any threat,' he said.
