Beijing (CNN) -- Design flaws in the railway signal equipment led to Saturday's fatal high-speed train collision in China which left at least 39 people dead, the Shanghai railway bureau said Thursday, in quotes carried by the state-run Xinhua agency.
The news comes as the Chinese government tightened its grip on coverage of the crash by major state-run news outlets amid a torrent of public anger and skepticism on social media over its handling of the incident.
Although it still dominated headlines across China's cyberspace Tuesday night, the accident in eastern Zhejiang province had been relegated to story No. 5 in the main newscast of national broadcaster China Central Television, and what was left of its coverage focused on the heroism of rescuers.
One story CCTV has remained committed to is that of Xiang Weiyi, with almost hourly updates Wednesday on her condition. The 2-year-old girl was pulled out of the wreckage alive 20 hours after a bullet train was struck from behind Saturday night by another train, killing at least 39 people -- including her parents.
"This is our responsibility, our way of consoling her deceased parents," said Wang Jianman, a vice governor of Zhejiang, pledging to provide Xiang with top medical care after visiting her at the hospital.
The plight of "Little Yiyi" -- as the girl has been affectionately called -- along with the images of heroic rescuers, caring officials and a concerned public, has fit perfectly the theme of "great love in the face of great tragedy."
That theme for the coverage was mandated in a directive issued Sunday by the central propaganda department -- as shown in a widely circulated photo of a Chinese journalist's cell phone screen. In the same order, domestic media was barred from questioning official statements or investigating the causes of the crash.
CNN cannot independently verify the photo's authenticity, and calls to the propaganda authorities Wednesday went unanswered.
In sharp contrast to Xiang, the face that has been conspicuously missing on CCTV is that of Yang Feng, a 32-year-old Zhejiang native who lost more family members than anyone else in the accident: wife, niece, mother-in-law, sister-in-law, and his unborn child.
Several videos of Yang's passionate remarks to local media have spread like wildfire online. Donning mourning clothes, he accused railway authorities of prematurely stopping the search-and-rescue operation after less than six hours and ignoring his pleas for help at the crash site.
"They saved this one girl, but had they continued their effort 15 hours earlier than her rescue, they might have saved three, four or five more lives," a grief-stricken Yang says in one video clip.
While CCTV shunned him, Yang became an overnight hero in the eyes of Chinese netizens who were riled by the government response to the accident, especially the perceived ineptitude and arrogance of the railway ministry. Less than 24 hours after he posted his first message on Weibo, China's equivalent of Twitter, Yang has gained more than 110,000 followers.
"The closer you get to the centrally controlled media, the more they toe the Communist Party line," explained Jeremy Goldkorn, a long-time Chinese media observer whose Danwei website monitors the industry. "For this accident, Weibo posts have been so far ahead of official responses."
Chinese netizens have been fuming over the government decision to crush and bury one of the six derailed train cars when the investigation had barely started, alleging an attempted cover-up or worse. In an apparent nod to the growing online opposition, crews excavated the buried car Tuesday night and transported it to a depot for re-examination.
For Weibo users, however, any sense of vindication may prove short-lived. Analysts say Internet censors have already begun deleting more posts as netizens became critical of not just the scandal-plagued railway ministry but also of the flaws of the political system.
"They are trying to shove the genie back in the bottle," media observer Goldkorn said. "Weibo is such an effective amplifier of people's dissatisfaction that it is worrying the government a lot."
Now Yang has turned uncharacteristically quiet. Pleading for his supporters' understanding, he alluded in his most recent Weibo posts that he was under tremendous pressure to keep a low profile for the well-being of his family -- including his father-in-law, who survived the train crash.
One goal, though, seems unshakable for both Yang and Xiang's guardians. Asked separately by local media about their demands to the government, their answers sounded the same: "We don't want money -- we want the truth."
CNN's Haolan Hong contributed to this report.