Families and friends are mourning the loss of 12 people killed in a plane crash on New Year’s Eve in Costa Rica.
Among the dead are 10 Americans ― two families and their tour guide ― and two Costa Ricans who piloted the Nature Air flight.
Investigators are still working to determine what caused the small Cessna plane to crash into a mountain, killing everyone aboard, shortly after takeoff Sunday in the Guanacaste region of northwest Costa Rica. Early theories included mechanical malfunction, human error and a patch of strong wind, a Costa Rican aviation official told The New York Times.
Here’s what we know so far about the victims:
The Steinberg Family
Bruce Steinberg, 50, and Irene Steinberg, 51, had been on vacation in Costa Rica with their three sons: Zachary, 19; William, 18; and Matthew, 13. All five family members died in the crash.
The family lived in Scarsdale, New York, an affluent town in Westchester County. Bruce was an executive at Bridgewater Associates, an investment management firm based in Westport, Connecticut. Irene volunteered with several nonprofit organizations.
Matthew was in eighth grade at the Ethical Culture Fieldston School, a private school in the Bronx. William and Zachary were students at the University of Pennsylvania and Johns Hopkins University, respectively.
“They were an incredibly tight-knit family who just loved to explore, loved to live life,” Paul Rubin, a family friend, told the Times. “They traveled extensively, but also gave their time extensively.”
The Weiss Family
Like the Steinbergs, Mitchell Weiss, 52, and his wife, Leslie, 50, had been enjoying a family vacation with their children ― daughter Hannah, 19, and son Ari, 16 ― at the time they were killed in the crash.
The Weiss family lived in Belleair, Florida, roughly 25 miles west of Tampa. Both Mitchell and Leslie were licensed physicians at Morton Plant Hospital in Clearwater. Mitchell was the head of the hospital’s interventional radiology department and Leslie was a pediatrician.
“Their lives and medical skills have touched so many in and around our community, and we are forever grateful to them,” Kris Hoce, president of Morton Plant Hospital, said in a statement.
Hannah was a student at List College, an undergraduate program at the Jewish Theological Seminary in New York City, which partners with Columbia University to allow students to earn two bachelor’s degrees simultaneously, according to the Times.
Ari was a sophomore at Shorecrest Preparatory in St. Petersburg and loved singing and acting.
“He was such a good person,” Chloe Schnitt, a classmate of Ari’s, told the Tampa Bay Times. “Everybody loved him.”
The family was active in their Jewish community. Both Hannah and Ari were youth leaders in the New York-based United Synagogue of Conservative Judaism. Leslie was a board member of Congregation B’nai Israel in St. Petersburg.
“This family was so bright and kind and will be missed by so many,” Congregation B’nai Israel posted on Facebook.
Geissler, 33, was a tour guide for Backroads travel company, where she had worked since May, according to her LinkedIn profile. She had been leading a tour for the Steinberg and Weiss families in Costa Rica that included “seeing an active volcano, 400-foot waterfall, and many beautiful beaches,” her family said in a statement.
“She was very excited to be working with families, and was eager to enjoy the sunshine, warm weather, and ocean waves,” the Geissler family wrote in the statement.
Geissler received an undergraduate degree in biology from the University of Wisconsin-Stout and a Master of Business Administration from the University of Wisconsin-Milwaukee.
During her undergraduate years, Geissler was a star of the UW-Stout women’s basketball team. Mark Knoll, a former assistant coach for the team, called Geissler “very special” and “kind” in a Facebook post.
Nature Air confirmed the identities of the two pilots killed in the crash as Juan Manuel Retana and Emma Ramos, according to Reuters. Former Costa Rica President Laura Chinchilla tweeted that Retana was her cousin.
This is a developing story. Check back for updates.
This article originally appeared on HuffPost.