Chinese media say more than 1,000 firefighters are still at the scene, with some fires still burning.
More than 200 chemical and biological experts from the military are on site.
President Xi Jinping and Premier Li Keqiang have vowed to hold a thorough investigation and ensure “open and transparent information disclosure to the public”.
China has also ordered a nationwide check on dangerous chemicals and explosives.
In a report, Xinhua said the cabinet, the State Council, had ordered “governments at all levels to reinforce the safety management”.
They should “firmly implement special regulatory measures for highly toxic chemicals such as cyanide, as well as inflammable and explosive materials”.
Is it safe?
Reuters reported that, according to a 2014 government assessment, the Ruihai facility was designed to store chemicals including butanone, an explosive industrial solvent, sodium cyanide and compressed natural gas.
The company also reportedly handles toluene diisocyanate, which is used in the production of flexible polyurethane foams.
Officials have confirmed that calcium carbide, potassium nitrate, ammonium nitrate and sodium nitrate were at the warehouse.
Xinhua said on Thursday that drains from Tianjin to the Bohai sea – a gulf in the Yellow Sea – had been closed “to stem a chemical leak”.
However, one official on Friday insisted the “air and water in Tianjin is safe”. ∞∞∞∞∞ MORE »»»»