In the hours since a 63-year-old man rammed his car into a sports centre in Zhuhai, killing 35 people and severely injuring 43 others, questions have swirled on Chinese social media about why it took authorities so long to reveal the details.

The driver, identified by his family name of Fan, was discovered in the car with self-inflicted knife wounds to his neck. Police said their preliminary investigation suggested he was dissatisfied with the split of assets in his divorce.

But little of that, or the full scale of the casualties, was known until a full day later.

Immediately after the incident, the deadliest mass killing in a decade, searches about what had happened were heavily censored, videos of the scene posted to social media were deleted, and early state media reports were removed from the internet.

It was only after the police released their report on Tuesday evening that news articles appeared in state media, and social media users could discuss the event more freely.

“This happened yesterday, but we only found out about it today. If it happened in other places, our media might have been following the news all day long,” said one Weibo user shortly after the police statement was released on Wednesday.

After the details emerged, people flocked to light candles and lay flowers at a makeshift vigil outside the sports centre, the site of the apparently deliberate car attack.

There was a light police presence outside the complex, which was closed until further notice, but the number of officers increased as the morning passed.

After initially allowing journalists to briefly speak to the people laying the flowers, a handful of security personnel sporting light blue uniforms and caps told reporters not to talk to the people or to film specific messages on the bouquets.

While police allowed people to leave bouquets of flowers in memory of the dead just outside the entrance , volunteers then quickly moved the flowers inside to the sports center.

Delivery drivers on motor-bikes kept dropping off fresh flowers on Wednesday morning, even as authorities erected temporary barriers around the makeshift vigil area.

People asked on social media to ask why they didn’t know about the attack sooner.

A 50-year-old man who identified himself as Zheng who brought flowers to the site said: “The authorities hadn’t released any information – some colleagues mentioned it and I couldn’t believe it at first, but it was confirmed later.”

“If I remember correctly, the Itaewon stampede at the end of 2022 was on the [Weibo] hot search for at least a week,” said one, referring to the deadly incident in Korea.

“There is an airshow in Zhuhai today, maybe they are afraid of affecting its activities,” said another, referring to the People’s Liberation Army airshow scheduled to begin on Tuesday. Many others also questioned the man’s motive as provided by police.

By Wednesday afternoon the discussion was still appearing on Weibo but related hashtags – which consolidate popular topics – were restricted, with viewing statistics and search functions curtailed.

“Delete posts, close comments, reduce popularity, [Chinese flag emoji] is really safe and free,” said one post.

Foreign media efforts to cover the attack were also stymied. A video report from the BBC’s correspondent Stephen McDonell shows an unnamed Chinese man – who McDonell suggests is likely a local party official – yelling and trying to physically block him and his crew from filming.

Monday’s incident was the latest among a number of recent attacks in China in which suspects appeared to target random people, including schoolchildren. In October, a 50-year-old man was detained after he allegedly used a knife to attack children at a school in Beijing. In September, three people were killed in a knife attack in a Shanghai supermarket. That same month a minibus plowed into a crowd outside a Shandong school, killing 11 and injuring 13. It was reported as an accident.

Monday’s attack is the largest lost of life in an apparent deliberate incident since 2022, when a China Eastern pilot flew his plane into the ground killing all 132 passengers and crew on board, including himself. Analysis of the black box flight recorders by US officials – who were helping the Chinese investigation – suggested the pilot had forced the Boeing 737-800 plane into its catastrophic dive. But in more than two years Chinese authorities have never released a final report.

Under the increasing authoritarianism of China’s leader, Xi Jinping, the release of negative news and information has become particularly fraught, with frequent punishment of officials and media outlets.

During the pandemic, key information about the initial outbreak was not reported to global health authorities. Citizen journalists were arrested for reporting from Wuhan, and in subsequent years there was high skepticism over China’s infection figures. When a massive outbreak came in 2022 after Covid-19 restrictions were abruptly dropped, authorities stopped reporting cremation figures.

With Associated Press and Reuters