Washington, June 30 : US President Joe Biden and first lady Jill Biden will visit Surfside, Florida, on Thursday in wake of the collapse of a residential building there, the White House announced on Tuesday. "They want to thank the heroic first responders, search and rescue teams and everyone who has been working tirelessly around the clock, and meet with the families who have been forced to endure this terrible tragedy waiting in anguish and heartbreak for word of their loved ones to offer them comfort as search and rescue efforts continue," White House press secretary Jen Psaki told reporters aboard Air Force One. The death toll from the tragedy, which happened last Thursday, now stands at 11, with 150 more remaining unaccounted for, making the disaster on track to become the largest mass casualty event of the Biden presidency so far, the Xinhua news agency reported. While rescuers are still racing to find the missing ones, affected families have become increasingly devastated as the hope that their loved ones are alive dwindles. "It's difficult to put into words the devastation that this community is experiencing. Our hearts go out to all the families and loved ones that have been impacted by this event," Deanne Criswell, head of the Federal Emergency Management Agency (FEMA), said on Tuesday during a congressional hearing. Biden has declared a state of emergency for Florida, directing FEMA and the Department of Homeland Security to provide federal resources and assist local rescue efforts. The President and the first lady "want to make sure that state and local officials have the resources and support they need under the emergency declaration approved by the President for Miami-Dade, Florida," Psaki said while announcing the presidential visit. /IANS