BEIJING — China’s top security official has concluded that the East Turkestan Islamic Movement, a separatist group, was responsible for the deadly attack Monday in which a car mowed down pedestrians at Beijing’s Tiananmen Square before bursting into flames.

“The violent terrorist incident in Beijing was … orchestrated by the Eastern Turkestan Islamic Movement terrorist organization that is entrenched in central and west Asian regions,” security chief Meng Jianzhu was quoted as telling Hong Kong-based Phoenix Television during a trip to Uzbekistan to attend a security summit.

Separately, China’s CCTV revealed new details about Monday’s attack in which five people died: two tourists and three members of a family of Uighurs, a Muslim ethnic minority from northwestern China’s Xinjiang region, who were in the car used in the attack. They included the 70-year-old mother of the driver.

The state news network identified the car as a Mercedes sport-utility vehicle. It said eight people from three families had been plotting in the southern Xinjiang city of Hotan since September and that they had raised $6,572 for the project.

“They decided to set up a terrorist group,” CCTV reported on its microblog account.

The network reported that the group drove to Beijing in early October and scouted out the location in Tiananmen Square three times before the attack. Five members of the group left for Urumqi, the capital of the Xinjiang region, while the three relatives remained to carry out the mission, the network said. They were equipped with knives and about 100 gallons of gasoline used to ignite the SUV.

The East Turkestan Islamic Movement, named for an old Uighur name for Xinjiang, is a group that operates largely out of Afghanistan and Pakistan and is devoted to expelling the Chinese Communist Party from northwestern China. An associated group called the Turkestan Islamic Party took responsibility in 2011 for knife attacks and explosions in Xinjiang that left 40 people dead.

“This movement uses extreme violence and religion to create the maximum political impact,” Pan Zhiping, a retired professor from Xinjiang University, said Friday. “My Uighur friends absolutely hate it. Many Uighurs are the victims of an event like this, which will create more misunderstandings and worse ethnic relations.”

Monday’s attack was the first that succeeded outside of Xinjiang. Chinese security officials were unnerved by the location, under the enormous portrait of Mao Zedong on Tiananmen Square and around the corner from the Great Hall of the People, where Chinese President Xi Jinping and the rest of the top leadership were meeting at the time.

The Uighurs are a Turkic people more closely related to Uzbeks and Kazakhs than to Chinese. The Uighurs number about 9 million in China.