The incident – in which a sport utility vehicle drove along the pavement, crashed into crowds and caught fire at the capital’s best-known and most sensitive site – killed three people in the car and two tourists, according to Beijing police.
The square lies next to the Forbidden City, a former imperial palace and top tourist attraction, and was the location of pro-democracy protests in 1989 that were violently crushed by authorities.
In a notice to hotels, police identified two suspects and four car number plates, all from Xinjiang, in relation to a “major case” that occurred on Monday, the Global Times reported.
Police also instructed hotels to watch out for “suspicious” guests and vehicles, said the paper, which is close to the ruling Communist party.
It carried the details in its English-language edition, but the Chinese version did not mention Xinjiang.
Security guards from several hotels in Beijing confirmed they had received a police notice.
A version posted online by 64tianwang.com, a Sichuan-based human rights news portal, gave the suspects’ names, identity numbers and registered residences, while urging hotels to report potential clues.
Its veracity could not be confirmed by AFP.
Xinjiang is home to ethnic minority Uighurs, many of them Muslim.
State media have reported several violent incidents there and a rising militant threat, but Uighur rights groups complain of ethnic and religious repression, while information is tightly controlled.
Police have arrested 140 people in Xinjiang in recent months for allegedly spreading jihad, and killed 22 Uighurs in August in an “anti-terrorism” operation, the official news agency Xinhua reported earlier.
One of the suspects named in the reported notice was from Shanshan county, which includes Lukqun, where state media said 35 people were killed in June in what Beijing called a “terrorist attack”.
Ilham Tohti, a prominent Uighur intellectual, cautioned against using the Tiananmen incident to stigmatise the ethnic group or imposing tighter controls in the region, according to the web portal Uighurbiz.net.