Three people were killed when a jeep crashed into a crowd in Beijing's Tiananmen Square on Monday and burst into flames, state media said, as pictures showed a tower of smoke rising before the Forbidden City.
Immediately after the incident a security operation went into effect on the vast square, the site of pro-democracy protests in 1989 which were brutally crushed by the authorities.
Pictures posted on Chinese social media sites showed the blazing shell of the vehicle and a plume of black smoke rising near the portrait of communist founder Mao Zedong hanging on the towering wall of the former imperial palace. There were also police vehicles gathered, and crowds looking on.
Several of the pictures were deleted within minutes, streets leading to the square were blocked off, screens were erected and two AFP reporters were forcibly detained close to the site.
"A motor vehicle went into the crowd in front of the Tiananmen rostrum Monday noon," the official Xinhua news agency reported.
"The jeep driver and two occupants have been confirmed dead," it said, adding that "many tourists and police on duty" were injured by the vehicle.
Beijing transport authorities said on a verified social media account that a subway station next to the square had been closed at the request of police.
One 58-year-old Italian tourist said he had been visiting the Forbidden City when officers came in around noon and told everyone to leave.
Tiananmen Square is the symbolic centre of the Chinese state and is generally kept under tight security, with both uniformed and plain-clothes personnel deployed, many of them equipped with fire extinguishers.
News of the incident first trickled online Monday afternoon in reports from Chinese social media users on the scene.
Pictures they posted showed the flaming wreck surrounded by several police and emergency vehicles, directly in front of the sign on the Tiananmen gate reading: "May the great unity of the world's people last for 10,000 years."
Details on a motive were not immediately available, but Chinese social media users speculated that it could be intentional.
"Is this the 2013 Tiananmen self-immolation incident?" asked one poster. "There's still a person inside the car!"
Around 120 Tibetans have set themselves alight since February 2009 in Tibet itself and adjoining regions of China, in protest against what they see as Chinese oppression.