New explosions and fires have rocked the Chinese port city of Tianjin as one survivor was pulled out and authorities ordered evacuations to clean up chemical contamination more than two days after a fire and a series of blasts.

Meanwhile, angry relatives of firefighters missing in the disaster stormed a government news conference to demand information on their loved ones.

The death toll from Wednesday’s inferno and blasts has climbed to 104, including 21 firefighters, making the disaster the deadliest for Chinese firefighters in more than six decades.

Paramilitary policemen in gas masks examine unknown chemicals near the site of the explosion.

An unknown number of firefighters remain missing, and 720 people were injured in the rapid succession of explosions that began with a fire in shipping containers containing hazardous material at a warehouse.

Authorities pulled out one survivor from a shipping container yesterday, State media reported. Television footage showed the man being carried out on a stretcher by a group of soldiers wearing gas masks.

The government set up an exclusion zone three kilometres around the site of the explosions to clean up chemical contamination from sodium cyanide, according to media reports. Sodium cyanide is a toxic chemical that becomes combustible on contact with water or damp air.

Burning flames were spotted and explosions were reported by witnesses and state media. In one case, heavy smoke from a fire engulfing several cars rose up as high as 10 metres, accompanied by at least five explosions.

The death toll has climbed to 104, including 21 firefighters, making the disaster the deadliest for Chinese firefighters in more than six decades

Police and military personnel manned checkpoints on roads leading to the blast sites, and helicopters were seen hovering in the overcast sky. The air had a metallic chemical smell, and there was uneasiness over rain forecasts, although it was warm and windy.

“(The authorities) didn’t notify us at all,” said Liu Huan, whose son Liu Chuntao has been missing since late Wednesday.

“Our son is a firefighter, and there was a team of firefighters who lost contact. We couldn’t contact him.”

Liu Longwang said she had not heard any word on her son Liu Ziqiao, also a firefighter. “We are extremely worried. He’s just turned 18.”

State media reported that the casualties of the first three squads of firefighters to respond and of a neighbourhood police station have not yet been determined, suggesting the death toll could still go up.

Tianjin Fire Department head Zhou Tian said at a news conference that the explosions occurred just as reinforcements had arrived on the scene and were getting to work.

“There was no chance to escape, and that’s why the casualties were so severe,” he said. “We’re now doing all we can to rescue the missing.”