Within minutes of the immense chemical explosions that sent apocalyptic fireballs into the night sky over Tianjin, Zhou Haisen, 23, was making arrangements to leave town. He was terrified that poisonous gases would reach his apartment six miles from the scene, and his fears were swiftly reinforced by posts on Chinese social media. So he and his parents fled to his grandmother’s house an hour’s drive away.

Since last Wednesday’s still-unexplained accident, which killed at least 114 people and injured more than 700, the Chinese government has repeatedly insisted that effective measures are being taken to ensure that the air in Tianjin remains safe. But when rain fell on Tuesday, the city’s streets began to foam, and people reported burning sensations on their lips and elbows.

An environmental monitoring official denied that those phenomena had anything to do with the explosions, Chinese news outlets reported. Even so, Mr. Zhou will not be going home anytime soon.

“Of course, we don’t believe the government about the air,” he said in a telephone interview. “They’re always unwilling to tell the truth. I don’t want to bet my life on their words.”

Just as the military cleanup crews have been unable to extinguish the smoldering fire at the port facility in Tianjin, the Chinese authorities have struggled to contain mounting public anger and distrust. The system of information controls they deployed after disasters like the 2008 Wenchuan earthquake, the 2011 high-speed train crash and the ferry sinking in June does not seem effective this time.

The nation has watched in real time as government censors deleted online investigative reports, erased microblog posts and abruptly cut off a nationally televised news conference after local officials appeared unwilling to answer even basic questions about which dangerous chemicals were at the blast zone and why they had been stored close to residential areas.

“They are definitely trying to cover it up,” Yuan Ping, 30, a telecommunications worker whose apartment was heavily damaged in the explosions, said in a telephone interview. Ms. Yuan said she and her family were so frustrated by a lack of official support that they were considering suing the government and the company that owned the facility, Rui Hai International Logistics. “I wouldn’t believe even a single word from them,” she said. “The government is doing everything on the surface.”

Protests erupted in Tianjin over the weekend, as residents who had been forced out of their damaged homes joined with relatives of missing firefighters to demand compensation and information about their family members.

Suspicions of a cover-up are so widespread that the Communist Party’s official newspaper, People’s Daily, published an explicit denial and promised a transparent investigation. “What need would there be to hold back and cover up a safety incident?” it said. “How could it be possible for government bureaucrats to shield each other?”

Xinhua, the country’s official news agency, reported on Tuesday that the company’s license to handle hazardous chemicals lapsed in November and that it did not get a new one until June. The authorities also identified 10 senior executives of the company, including the chairman, Yu Xuewei, and the vice chairman, Dong Shexuan, who were detained on Thursday, a few hours after the explosions.

“The top level has paid attention to the issue of the Rui Hai company, no one dares to say a word,” a police officer told Caijing Magazine, which said four of the 10 executives were in a hospital.

Later on Tuesday, China’s anticorruption agency announced on its website that Yang Dongliang, a former deputy mayor of Tianjin who became the head of the State Administration of Work Safety, was under investigation for “suspected violations of party discipline and the law,” a common euphemism for corruption.

The Beijing Youth Daily reported, however, that Mr. Yang has been under investigation for a half-year, raising questions about why the case was announced now. Two other officials accused of taking bribes are also under investigation.

Rather than depend on official announcements, many Chinese look to social media, where a cat-and-mouse game is played between a public hungry for answers and censors anxious to scrub anything that might reflect poorly on the central government. Mr. Zhou said that even rumors were better than waiting for the authorities to publicly identify all the chemicals or name every firefighter who died in the blasts. “They’re either stupid or pretending to be stupid,” he said of the officials.

As they did after previous disasters, the Chinese authorities have tried to block reporting that makes the government appear to be at fault. After the 2008 earthquake in Wenchuan, the Central Propaganda Department forbade the Chinese news media to report on shoddy school construction, which had led to the deaths of thousands of children. In 2011, a leaked propaganda directive ordered the media not to reflect or comment on the train crash that killed 40 people, saying, “Do not investigate the causes of the accident.”

Public reflection on man-made tragedies is politically risky for the ruling Communist Party, according to David Bandurski, an editor of the China Media Project at the University of Hong Kong. “The party leadership is very aware that questions of responsibility in a disaster like this can very quickly move to fundamental issues of power and legitimacy,” he said, explaining that in an authoritarian system, “the buck stops with you.”

Mr. Bandurski noted that censors had struggled to control the Tianjin narrative because some Chinese journalists had pushed ahead with their own reporting. “This is a very messy story, and for Chinese media, messy means opportunity,” he said.

Even so, a day after the blasts in Tianjin, censors were already prohibiting the news media from privately gathering information on the accident or adding individual interpretations to official announcements, according to a leaked directive. Instead, the state media have mostly focused on publishing touching articles about the rescue operations, including one in People’s Daily titled “Puppy Saved From Tianjin Explosion Site.”

For Chinese people trying to understand the disaster, seeing a flood of sanctioned memorials and rescue stories without any robust reporting is frustrating.

“Lighting candles becomes a cheap and well-meaning emotional expression,” Jia Jia, a Chinese journalist and blogger, said in a telephone interview.

Mr. Jia posted a lengthy screed on a social media website a few days after the disaster, saying: “Pick up a leather lash, and flog hard those derelict in their duty, who treat human lives like dirt.” Censors swiftly deleted it and Mr. Jia’s entire public profile from social media.