The death toll from the tank-rupture incident at a Washington state paper mill on Tuesday rose to two, with nine people still missing and presumed dead, authorities said.

The Longview fire department said in a statement on Wednesday afternoon that one person who was transported to the hospital following the disaster at Nippon Dynawave Packaging Co on Tuesday morning had died.

“We’re bracing ourselves for this being the deadliest industrial tragedy in modern Washington state history,” Washington governor Bob Ferguson said at a news conference with local authorities on Wednesday.

The agency said that recovery efforts began at the mill on Wednesday following a delay due to “safety concerns of the structural integrity of the damaged tank”. Authorities have said there is no hope of finding any additional survivors and that the operation had transitioned from rescue to recovery.

Meanwhile, a team of investigators with the US Chemical Safety and Hazard Investigation Board (CSB) was set to arrive on scene Wednesday after the federal agency announced it was launching an investigation into the fatal implosion.