The attack happened on the far side of China, in Xinjiang region, near the Afghan-Pakistan border, and as far as Beijing as you can get, but Chinese authorities think it could be timed to the games. State media say 16 policemen were killed in the city Kashgar.
"The World" anchor Lisa Mullins talks to the BBC's Daniel Griffiths in Beijing.
Griffiths says the region of Xingjian is very different from other parts of China – it is home to large deserts and mountain ranges, and 7 to 8 million of its people are Muslim.
According to Griffiths, this morning two attackers driving a truck drove into a group of police officers who were out doing their morning exercises. The two attackers jumped from the vehicle and threw grenades, which exploded, and also attacked the police officers with knives. The Chinese authorities are calling this a terrorist attack.
PRI's "The World" is a one-hour, weekday radio news magazine offering a mix of news, features, interviews, and music from around the globe. "The World" is a co-production of the BBC World Service, PRI and WGBH Boston. More "The World."