Scores of Chinese firefighters are still missing following the massive explosions that hit an industrial area in Tianjin, officials have said.

At an official press conference on Sunday, authorities announced that the death toll had risen to 112, but added that 95 people had been confirmed missing - including 85 firefighters.

Al Jazeera's Adrian Brown, reporting from Tianjin, a port city in the country's northeast, said it was now possible that the death toll will climb past 200, "making it one of China's worst industrial accidents".

Authorities evacuated residents living near the industrial site on Saturday as fears spread that toxic substances were spreading.

 Al Jazeera's Adrian Brown reports from Tianjin

The list for the missing is getting longer. It stretches for more than four metres outside a school that is now accommodating hundreds of homeless families.

Most of those yet to be found are fire fighters - 85 of them. At least 21 are already confirmed dead - the youngest was just 17.

Close up the disaster zone looks like the aftermath of a nuclear disaster.

Clouds of grey and black smoke billow over an apocalyptic land scape. This feels like China's Fukushima moment. What is clear is that we will end with a death toll well over 200, making this one of China's worst ever industrial accidents.

On Sunday, Prime Minister Li Keqiang became the first government leader to visit the city. He went inside the exclusion zone, pointedly not wearing a face mask.  An image, no doubt, that is meant to reassure a jittery public who are being asked to believe the air is safe, even though the government still don’t know what caused Wednesday’s multiple explosions. What they now admit though is that sodium cyanide was stored at two locations at the blast site.

Gas masks are now the most precious commodity in this port city.  But the ones we saw today were for the military. But there clearly aren’t enough, and even if they were the ones won’t protect you from sodium cyanide.

My colleagues and I have military grade bio chemical masks. It could make all the difference in this uncertain and frankly frightening environment.

Brown said that officials have still not been able to identify the cause of the explosion, but the disaster is believed to have started at a warehouse of shipping containers with hazardous materials.

"What the people in this city want is reliable information," he said.

Officials have listed a litany of chemicals that may have been at the hazardous goods storage facility when the explosions happened, but have been unable to say precisely which ones were present.

Potassium nitrate and ammonium nitrate are believed to have been there.

Chinese reports said 700 tonnes of sodium cyanide were at the site, and officials called in experts from producers of the material to help handle it. Hydrogen peroxide, which neutralises it, has been used.

The explosions occurred after firefighters were called to a blaze at a hazardous chemicals storage facility on Wednesday night in an industrial zone of Tianjin, one of China's biggest cities with a population of 15 million people.


GALLERY: Deadly inferno - The aftermath of the massive Tianjin explosions


Then, two massive explosions took place about 11:30pm (15:30 GMT), sending a giant fireball sweeping across the area.

Residents likened the shockwaves to an earthquake, and aerial footage of the blast zone shows scenes of monumental devastation, with buildings burned out, shipping containers crushed and tumbled like piles of children's blocks, and fields of burned-out vehicles.

About 10,000 new imported cars near the blast site were destroyed, according to Chinese media reports, and even buildings three kilometres (1.9 miles) away had their windows shattered.

Tianjin residents, relatives of the victims and online commentators have criticised local authorities for a lack of transparency, including at one point trying to storm a news conference on Saturday.

On Sunday, sobbing men confronted security at the hotel where officials have been briefing journalists, with one shouting "Police, I will kill someone!" in what appeared to be a desperate bid to draw attention before being comforted by a policeman, the AFP news agency reported.

Another lashed out at reporters attempting to photograph him, saying: "Don't take my photo, it is useless. The news has no truth!"

The government has moved to limit criticism of the handling of the aftermath, with a total of 50 websites having been punished for "creating panic by publishing unverified information or letting users spread groundless rumours", according to the Cyberspace Administration of China.

Critical posts on social media have also been blocked, and more than 360 social media accounts have been suspended or closed down.

About 10,000 new imported cars were destroyed in the blasts [Reuters]

Source: Al Jazeera and agencies