Joe Raedle/Getty Miami condo collapse
Officials are conducting DNA testing to help identify the victims of the collapse of Champlain Towers South condo outside of Miami.
As rescue workers search for the 159 unaccounted people in the tragic incident, family members of suspected victims are encouraged to take a DNA swab at the reunification site at the Family Assistance Center at the Surfside Community Center located at 9301 Collins.
Surfside Commissioner Eliana Salzhauer first told PEOPLE on Thursday that DNA samples were being collected to match family members with the missing.
Miami-Dade County Mayor Daniella Levine Cava also confirmed on Friday that family members have been taking DNA swabs. "We have done DNA identification," she said on MSNBC, adding that many families "offered their DNA for matching."
"And as soon as a person is identified through our victim advocates, through our medical examiner's office, the first to be notified will be next of kin," she added.
Joe Raedle/Getty Images Miami-Dade Fire Rescue personnel search for survivors
As of Friday morning, the death toll from the condo collapse has risen from one to four, Cava announced in a press conference. The number of unaccounted for people rose from 99 to 159.
Robert Allen, a professor of forensic sciences at Oklahoma State University's Center for Health Sciences, told NBC News DNA of victims is likely to be "be fully intact" even through injuries. He explained the hypothesis is because there aren't any suspected elements of the collapse that would cause accelerated decomposition.
Allen told the outlet too that in the event that a victim doesn't have DNA from family available for immediate comparison, dental records and fingerprints are options for identification.
Miami-Dade Fire Rescue/Twitter The aftermath of the collapse of the Surfside Condo
In addition to the reunification center, officials have set up a family reunification hotline number (305-614-1819) and Miami-Dade Fire Rescue is encouraging tenants of the building to complete a Wellness Check Form to ensure everyone is accounted for.
As of Friday morning, 120 people have been accounted for, Cava said during a press conference.
During the briefing, Miami-Dade Fire Rescue Chief Ray Jadalla said officials "have hope" for finding survivors within the debris, as they focus rescue efforts on areas they have heard sounds.
"The entire building - the portion that's still standing - was cleared by rescue crews. So at this point now, all resources have been shifted to the rubble, including from above and from below," he said. "Every time that we hear a sound, we concentrate on that area."
The cause of the collapse remains unknown and Miami-Dade Police Department is conducting an ongoing investigation.