(CNN) -- Len Gengel cries between sentences. "It's my daughter's birthday today," he says, choking back tears. "We should be celebrating," he says. "Instead, I'm talking to people all day long, making sure they continue on the search and rescue. That's my objective today: to keep that search and rescue going." Gengel's daughter, Britney, is one of four students from South Florida's Lynn University who are missing amid the rubble of Haiti's Hotel Montana. Two faculty members from the university also remain missing. Britney, a sophomore journalism major with jet black hair and a bright smile, turned 20 Thursday. She had traveled to Haiti with 12 Lynn University students on a humanitarian mission to feed the poor. Eight of the students were rescued last week.
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Today is Britney Gengel's 20th birthday; she remains missing in Haiti
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"Think of the worst day of your life and then times that by 1,000," father says
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Britney was among 12 college students in Haiti on humanitarian trip
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Her family was initially told Britney was rescued
He continues to pray for others missing at @placeholder and across Haiti.