Beijing police said the perpetrators were a man with an ethnic Uighur name, his wife and his mother. Police also have arrested five people identified with typically Uighur names on suspicion of conspiring in the attack and called it a planned terror strike the city's first in recent history.
Knives, iron rods, gasoline and a flag imprinted with religious slogans were found in the vehicle, police said.
Uighurs are an ethnic minority residing mainly in China's northwest region of Xinjiang, and they have close cultural and language ties to Turkic peoples of Central Asia.
China believes the East Turkestan Islamic Movement aims to establish an independent East Turkestan in Xinjiang, and blames the group for the low-intensity insurgency in the region.
The United States placed the movement on a terrorist watch list following the Sept. 11 attacks, but quietly removed it amid doubts that it existed in any organized manner.
Instead, human rights groups have questioned whether China uses the security threat as an excuse to suppress the Uighurs and said Uighur extremism has been fueled by China's heavy-handed policies in Xinjiang and discrimination against Uighurs by the country's ethnic Han majorities.
Uighurs say they've seen little benefit from the exploitation of Xinjiang's natural resources while good jobs tend to flow to ethnic Han migrants. The 9 million Uighurs now make up about 43 percent of the population in a region more than twice the size of Texas where they used to dominate.
Following Monday's attack, police have set up checkpoints and stepped up security in Xinjiang , according to various reports.
