U.S. Army captain, brothers, a law student, international aid workers among the 157 killed in an Ethiopian Airlines crash

Making the world a "better place" was how heartbroken family members will remember loved ones who were among the 157 people aboard the Ethiopian Airlines flight that crashed just minutes after takeoff on Sunday morning.

No one survived the horrific crash that claimed the lives of a decorated U.S. Army captain, brothers on vacation, a law school student and dozens of international aid workers.

Thirty-five countries from all over the world lost citizens in the deadly incident, with Kenya losing the most -- 32 nationals.

At least eight U.S. citizens were among the victims. The U.S. Embassy in Ethiopia and the U.S. Department of State haven't released their identities, but ABC News has confirmed the names of four.

Antoine Lewis, 39, of Matteson, Illinois, was a U.S. Army captain stationed in Ottawa, Canada, who served in Afghanistan. He was on vacation in Ethiopia doing Christian missionary work, according to his parents. They said Lewis equally valued the country he fought for and the home of his ancestors.

"That’s what he died doing," his mother, Antoinette Lewis, told ABC Chicago station WLS in a recent interview. "His passion was just to make a better world, make a better place, both here and our mother country."

Lewis leaves behind a wife and a 15-year-old son.

"I’m still in disbelief," his wife said in a statement obtained by ABC News. "I feel it's a dream [I'm still] awaiting his call to tell me he has safely touched down."

"Antoine was so loving," she added. "He was always interested in learning new things, forever on a journey becoming a better version of himself each day. He was so smart and just wanted to share his wealth of knowledge with those who’d listen."

Ike and Susan Riffel of Redding, California, lost their only children in the crash, Bennett and Melvin Riffel. The brothers were on vacation traveling to a few different countries as part of an adventure ahead of the birth of Melvin's first child, according to the family.

Melvin and his wife, Britney, were expecting a baby girl in May.

"We appreciate the outpouring of love and support from the community," a spokesperson for the Riffel family told ABC Redding affiliate KRCR in a statement. "We ask for continued prayers."

IQAir, a Switzerland-based company that specializes in improving indoor air quality, confirmed that one of its employees, Matt Vecere, was aboard the doomed flight. Vecere grew up in Sea Isle City, New Jersey, and later moved to California.

"Matt was an amazing writer, an avid surfer, and a truly selfless person," IQAir said in a statement. "He was most at home helping others, as evidenced by his dedication to the people of Haiti following the devastating earthquake in 2010."

"We will miss his laugh, his wit, his sense of humor, but most of all, the kinship and friendship that he brought to everything he did," the company added.

Ethiopian Airlines identified the pilot of the ill-fated plane as Yared Mulugeta Gatechew, who had more than 8,000 flight hours. The co-pilot was Ahmed Nur Mohammod Nur, who had over 200 flight hours.

The United Nations said at least 21 of its employees were among those killed in Sunday's crash.

The staffers hailed from around the globe and worked for various U.N. agencies, which regularly made trips to Kenya by way of Ethiopia to visit Africa's United Nations Office headquarters, located in Nairobi. Many were traveling to attend a five-day assembly of the United Nations Environment Programme.

The World Food Programme (WFP), the food-assistance branch of the United Nations, released the names of seven team members who died: Ekta Adhikari, 26, of Nepa; Maria Pilar Buzzetti, 30, of Italy; Virginia Chimenti, 26, of Italy; Harina Hafitz, 59, of Indonesia; Zhen-Zhen Huang, 46, of China; Michael Ryan, 39, of Ireland; and Djordje Vdovic, 53, of Serbia.

"As we mourn, let us reflect that each of these WFP colleagues were willing to travel and work far from their homes and loved ones to help make the world a better place to live," the WFP's Executive Director David Beasley said in a statement. "That was their calling, as it is for the rest of the WFP family."

The Office of the United Nations High Commissioner for Refugees named three colleagues who also died: Nadia Ali, 40, of Sudan; Jessica Hyba, 43, of Canada; and Jackson Musoni, 31, of Rwanda.

"We’ve been struck by sudden and terrible loss," U.N. High Commissioner for Refugees, Filippo Grandi, said in a statement. "We are doing everything we can to help Nadia’s, Jessica’s and Jackson’s families at this most difficult and painful time."

The United Nations Environment Programme (UNEP) said it lost a program officer in the gender and safeguards unit, Victor Shangai Tsang, of Hong Kong, China.

"Victor took up this position with vigor and enthusiasm, striving to make our projects fully gender-sensitive," UNEP said in a statement. "His work defined him as an individual, and he, in turn, helped define our own work."

Victor leaves behind his pregnant wife and son.

The Food and Agriculture Organization of the United Nations confirmed it lost fisheries officer Joanna Toole, who was "passionate about making the world a better place."

Another victim in Sunday's plane crash was Max Thabiso Edkins, a 35-year-old dual-national of Germany and South Africa. He worked as a communications officer for the World Bank's Connect4Climate program.

"We were devastated to learn that we lost a cherished colleague in the plane crash in Ethiopia," the World Bank Group's interim president, Kristalina Georgieva, said in a statement. "Max was deeply committed to the fight against climate change and brought tremendous creativity, energy and passion to his work. Our deepest sympathies go to his family and loved ones, and to those of the other victims of this tragedy."

Cedric Asiavugwa, a third-year law student at Georgetown University in Washington, D.C, was traveling to his native Kenya to attend the funeral of his fiance's mother, according to a press release from the school.

Born and raised in Mombasa, Kenya, Asiavugwa's work on social justice issues led him from his native country to Uganda, Tanzania and Zimbabwe, before coming to Georgetown University Law Center. The 32-year-old planned to return home to Kenya after graduating to continue serving refugees and other marginalized groups.

"With his passing, the Georgetown family has lost a stellar student, a great friend to many, and a dedicated champion for social justice across East Africa and the world," the law school said in a statement.