The breakthrough in the probe came as Beijing police captured the five suspects with the cooperation of authorities including those in northwest China's Xinjiang Uygur Autonomous Region that borders PoK and Afghanistan.
The car crash incident at the Tiananmen Square in the heart of the capital is still shrouded in mystery as details of Monday's attack remain sketchy.
The attack was "carefully planned, organised and premeditated," a spokesman with the Beijing Municipal Public Security Bureau said.
Usmen Hasan, his mother, Kuwanhan Reyim, and his wife, Gulkiz Gini, drove a Sports Utility Vehicle (SUV) with a Xinjiang plate to crash into a crowd of people on October 28 killing two people and injuring another 40, the spokesman said.
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The two people killed included a Philippine female tourist and a male tourist from south China's Guangdong Province.
The three people in the SUV died after they set gasoline on fire, the spokesman said.
Earlier media reports said police were looking for eight suspects all from Xinjiang. The SUV carried a flag and displayed extremist slogans.
Monday's attack was their biggest outside Xinjiang.
Some tourists said they heard an explosion. Also the car went up in flames near the life-size picture of the ruling Communist Party founder Mao Zedong, which however remained intact.