Former Montgomery County residents along with a University of Pennsylvania student and his family were among the 12 killed in a fiery plane crash in Costa Rica Sunday.

A total of 10 Americans and two local crew members were aboard the single-propeller Cessna 208 operated by Nature Air, a regional airline in Costa Rica, according to government reports. The plane crashed in the Guanacaste area shortly after takeoff, according to Costa Rica's Ministry of Public Safety.

William Steinberg, an 18-year-old freshman at Penn, along with his parents and two brothers from Scarsdale, N.Y., were traveling on a family trip, the university said.

"All of us, as Penn family members, are thinking of William's family members and friends as they move through this terrible loss," Valarie Swain-Cade McCoullum, Penn's vice provost for university life, said in a message to the undergraduate community Tuesday. "Our hearts are full, and we give them our deepest sympathy."

Steinberg had participated in PennQuest, an outdoors experience for first-year students, and was also involved with the Seeds of Peace organization, the school said. An on-campus remembrance is being planned for next week.

"Will was strong, empathetic, and believed in the beauty in the world and humankind," his aunt, Tammy Steinberg Jacobson, said in a statement released by Penn.

The University of Pennsylvania's Class Board 2021 shared its condolences in a Facebook post Monday.

"We are very shocked and saddened to hear about the death of William Steinberg and his family," the message read. "We still cannot believe that they died so unexpectedly. Many of us knew Will very closely, he was such a wonderful person who blessed Penn with his amazing smile everyday. Together we mourn the death of a friend, a peer, and a promising scholar who would have went on to change the world."

Former Montgomery County residents Leslie Levin Weiss, 50, and her husband Mitchell Weiss, 52, were also among those killed, according to a government agency and news reports from the Central America country.

Also listed among the dead were Hannah Mae Weiss, 19, and Ari Moses Weiss, 16. It was not immediately clear whether they are children of Leslie and Mitchell Weiss. Records show Hannah Weiss sharing their address in Florida.

Leslie and Mitchell Weiss left the Philadelphia area around 2005, relocating to Belleair, Fla., according to public records. They were both licensed as practicing physicians affiliated with local hospitals. The couple had previously lived in Plymouth Meeting and Lafayette Hill.

Costa Rican President Luis Guillermo Solís Rivera posted his condolences to Facebook.

Authorities said it only had a list of the plane's passengers and were awaiting official confirmation of their identities, according to the Associated Press.