The crash during lunch hour Monday killed five people including the driver and two passengers in the vehicle and two more pedestrians and injured 38 more people.
It was not clear if the incident might have been terror-related or a self-immolation protest.
The Los Angeles Times reported Beijing authorities searched the capital Tuesday for two suspects from Xinjiang-Uighur region northwestern China. The region has a large Muslim population and has been the scene of many violent demonstrations that have claimed dozens of lives as the Uighurs seek greater autonomy.
The report, quoting a police notice, said the suspects' names identified them as Uighurs.
The Washington Post, citing FreeWeibo.com, said Chinese censors had deleted numerous posts that began appearing on Chinese social media sites after the incident.
So far, Chinese official media reports on the incident have said the vehicle, identified as a Jeep, crashed into a crowd in front of the rostrum at the popular tourist attraction and iconic Tiananmen Square in the Chinese capital, killing five people and injuring 38 more including tourists and policemen. The vehicle, with some reports identifying it as an SUV, later burst into flames.
Authorities cleared the Tiananmen Square, where security has always being tight since the bloody 1989 pro-democracy student demonstrations which were crushed by authorities. The area was later reopened.
The New York Times said those killed included the driver of the vehicle, two passengers and two pedestrians. One of the pedestrian was a woman from the Philippines and the other a Chinese man.
The Post said some of the deleted posts suggested the incident may have been a case of self-immolation, such as those committed by Tibetans protesting Chinese rule of Tibet.
The Post said authorities also had blocked Internet searches for "Tiananmen car accident."
The Post, quoting a Beijing police microblog, said the vehicle ploughed through the security barriers of the square and crashed into a stone bridge to the former imperial palace known as the Forbidden City before catching fire.
The New York Times also reported that Chinese authorities, seeking to contain the coverage of incident, had deleted witness photographs and other postings on social media, and that the Chinese Foreign Ministry declined to answer a question about whether the incident might have been a terrorist attack.
Some witness accounts suggested the driver purposely steered the vehicle more than 400 yards along the sidewalk before ramming it into a marble railing of the Jinshui Bridge.
"This was not some driver who took a wrong turn and accidentally ended up on the sidewalk," one witness said.
The Wall Street Journal reported tourist again filled the square when it reopened with armed police and plainclothes officers resuming their patrol. There were no signs of the incident when the place reopened.
The BBC said its news team was detained at the square for about 20 minutes after the incident. The report said the metro station closest to Tiananmen Square was closed for more than three hours after the crash.
The Los Angeles Times, referring to the search for two suspects, quoted police that all hotels in the city would be required to report guests who had registered since Oct. 1 and the cars they had driven in order "prevent the suspects and vehicle from committing more crimes."
The report said the government appeared embarrassed by the apparent lapse in security in the heart of the city. The city is preparing for a plenum of senior members of the Communist Party next month at the Great Hall of the People, which is on the west side of the Tiananmen Square.
Ilham Tohti, a note Uighur economist in Beijing, urged Chinese authorities not to jump to conclusions about Uighur involvement in the incident, the report said.
"If there's no evidence, they should not say it is Uighurs who did it, and they shouldn't make the conclusion that Uighurs are involved in terror attacks," Tohti wrote on his website. "But we also can't rule out the possibility that some Uighurs might have wanted to express their grievances through extreme measures."