BEIJING –Trying to work out what on earth happened Sunday night in Urumqi, where the government says that at least 140 people died in a riot, is proving about as hard as getting an interview with President Hu Jintao.

The key question is: Who died? Muslim Uighur demonstrators, cut down by the police, as Uighur exile groups claim? Or innocent Han Chinese bystanders, butchered by a mob of Uighurs, as the government-owned media are making out?

Getting any Uighurs in Urumqi to talk on Monday was impossible. Their Internet access had been cut off, most of their phones, too, and those whom foreign journalists reached were too terrified of the government to say anything.

Xinjiang, an allegedly autonomous region, is the hardest place I have ever worked. The atmosphere of repression is Stalinist. For a week last year I tried to gauge ordinary people’s feelings there about the authorities. Not one person I spoke to would give his real name, and most whom I approached wanted nothing to do with me.

They knew I was being watched by the Chinese secret police, and they knew they would get into trouble for talking to a foreign reporter. Frankly, I did not call any Uighurs anywhere in China on Monday, for fear of the repercussions they would face for even getting a call from me.

But what was really astonishing was the reluctance of Chinese scholars to say anything about why they thought the riot had broken out. Perhaps because they did not want to diverge from the party line, perhaps because they did not yet know what the party line was, none of the local Xinjiang experts whom I called Monday would talk to me.

One simply hung up when I announced who I was. Another – a scholar of China’s border territories – said that he was working only on Tibet, not on Xinjiang. (When I called him last March to talk about Tibet, he told me that he had nothing to say because he was working only on Xinjiang….)

A third, his wife said, had been unexpectedly detained at a conference out of town and was mysteriously unreachable on his cellphone.

So, faced with a sensitive political issue, defenseless Uighur men-in-the-street and well-placed Beijing intellectuals all found themselves in the same boat: voiceless.