THE political heart of China is one of its most tightly controlled and patrolled patches of ground. Yet a constant police presence and surveillance cameras were not able to stop a Jeep from ploughing into concrete barriers at Tiananmen Square on Monday morning—just below Mao's portrait—killing five people, including the car's driver and two passengers, and injuring at least 38. There is no direct evidence that the collision was intentional. But explosive events at Tiananmen, which has long been the symbolic centre of Communist Party power in China, are almost always presumed to be. Authorities are on constant watch to prevent them. In the hours after the crash, police closed the square and established a massive presence in central Beijing; state agencies removed photos of the site from the internet and imposed a general clampdown on the national media. This all contributes to the sense that whatever happened was something more than an accident.

The fiery crash has been left unexplained in official channels, but that has not stopped a torrent of rumours and theories. Most have it that this was some sort deliberate grab for attention to some specific political issue.

Tiananmen and the Forbidden City, the centres of the capital and, by extension, China, are typically scenes of hushed tranquillity, which is enforced by hyper-vigilant security patrols. But when things happen anywhere in the capital, they tend to happen out in the open on or near the square, which is China's most public place for airing grievances. Mass demonstrations filled Tiananmen in both 1976 and in 1989. Both were crushed by the government.

These were not the first flames to have been seen in Tiananmen since then. Members of the Falun Gong, a quasi-Buddhist sect, tried using the square as a site for protest from 1999 until 2001, when a group of people was set on fire there (the government says the people who were burned were suicidal protesters from the Falung Gong, and used the event to discredit their movement effectively)*. And a farmer set off a bomb in 2001, killing one man.

This is not even the first mysterious car crash in Tiananmen. In 1982 a female taxi driver who had been fined at work drove her car across the square and smashed it into concrete barriers.

Today’s wreck, whether or not it was intended to make a point, came at the end of a weekend that was marked by a series of strange events around the core of Beijing. Just an hour before the crash, reports surfaced that a group of a seven or eight people caused a scene by linking arms and jumping fully clothed into a lake near the Forbidden City, the imperial palace that lies behind Tiananmen. Photos show the group huddled together, standing in the water.

It was also reported that on Friday October 25th a worker at the Forbidden City stabbed to death two of his co-workers, inside the palace’s cafeteria. Official media say the murders were the culmination of a dispute between employees.

* Correction:An earlier version of this post stated that the people who were burned to death in the square in 2001 were indeed members of the Falun Gong who immolated themselves in protest. While that remains the official account, the actual facts are substantially in dispute. This article was changed to reflect that on October 29th, 2013.

(Picture credit: AFP)