Investigators searched for clues on Friday to identify what caused two huge explosions at a warehouse storing volatile chemicals at a busy port in north-east China, as foreign and local companies assessed the damage to their operations.
The blasts in the city of Tianjin on Wednesday night killed at least 50 people, including a dozen firefighters, state media said.
About 700 people were injured, 71 seriously.
Rescuers pulled one survivor from the wreckage on Friday, a city official told reporters.
Columns of smoke from fires still burning rose from the blast site amid the devastation of crumpled shipping containers, thousands of torched cars and port buildings reduced to burnt-out shells.
The warehouse, designed to house dangerous and toxic chemicals, was storing mainly ammonium nitrate, potassium nitrate and calcium carbide at the time of the blasts, according to police.
Chemical safety experts said calcium carbide reacts with water to create acetylene, a highly explosive gas.
The explosion could have been caused when firefighters sprayed the calcium carbide with water, they said.
The official Xinhua news agency has said several containers in the warehouse had caught fire before the blasts.