An American aid worker was among 74 people killed in suicide bomb attacks in Uganda Sunday, at two sites where crowds had gathered to watch the World Cup final.
Six young missionaries from Pennsylvania were also injured in the bombings. A Somalia-based militant group with ties to al Qaeda has claimed responsibility.
The FBI has sent agents based at the U.S. Embassy in Nairobi, Kenya to assist in the investigation and look into the circumstances of the death of the American citizen, a State Department official in Washington said.
Nate Henn, 25, a native of Wilmington and a former University of Delaware rugby player, had raised thousands of dollars in the United States for Ugandan children's education and to help those affected by the long-running war there, and recently traveled to Uganda to meet the students
The children called Henn "Oteka," or the strong one, and they "fell in love with Nate's wit, strength, character and steadfast friendship," San Diego-based Invisible Children, a group that helps child soldiers, said in a statement on its website.
He was with some of them Sunday watching the Germany-Spain match on a large screen TV at the Kyadondo Rugby Club in Kampala when, according to eyewitness reports, a blast erupted, and then another.
"He sacrificed his comfort to live in the humble service of God and of a better world, and his is a life to be emulated," the group said in a statement.
"Nate was not a glory-seeker and never sought the spotlight. He asked not to be made a hero of. But the life he lived inspires reflection and imitation."
Henn's parents, who live in Raleigh, N.C., declined immediate comment. Early Monday, a truck delivered flowers to their two-story brick home in a quiet neighborhood among tall pine trees.
His sister Brynne Henn wrote on her Facebook page: "I just don't understand. Please pray."
Henn's former youth pastor, the Rev. Andrew Hudson, said Henn was a gentle, sincere young man with deep compassion for those in distress.
The pastor from Chelten Baptist Church in Dresher, Pa., said Henn knew that traveling in Africa could be dangerous. "Nate was willing to take that risk in order to provide hope and healing for precious children who were finding themselves in very difficult situations," Hudson said.
Henn was a psychology major at the University of Delaware from September 2003 to December 2008 but did not earn a degree, spokeswoman Meredith Chapman said. He played club rugby at the university in 2005-06 until an injury sidelined him, according to school officials and a teammate, Jason Vanterpool.
He was "always smiling, he was a really, really nice guy," Vanterpool said.
Former neighbor Melanie Mask recalled how Henn and other children would play football in the front yard of her home in the quiet, shady neighborhood in suburban Wilmington where he grew up. As a teenager in Wilmington, Henn volunteered at an orphanage and went on a church mission to Peru.
"He always wanted to help people; never met a stranger, ever," she said.
Mask described Henn as gregarious but sensitive, easily making friends in high school. She said girls vied to be his prom date and nicknamed him, "Nate the date."
In a terrible coda to the family tragedy, Nate's brother, Kyle Henn, was a passenger on a small private plane that crashed today just outside Horace Williams Airport in Chapel Hill, N.C. One person aboard was killed.
The single-engine Cirrus SR 20 crashed at about 3:15 p.m. Kyle told his family that he was unsuccessful in trying to pull the pilot from the plane after the crash.
A friend of the company Kyle Henn works for offered the private flight so he could be with his family after his brother's death, his sister told CBS Affiliate WRAL.
Kyle Henn was taken to UNC Hospitals in Chapel Hill for treatment, according to his sister. He was listed in fair condition. A second passenger on the plane was listed in critical condition.
"I Feel Like I'm in a Dream floating"
A group of young missionaries from central Pennsylvania who had gone to Uganda to help build a wall around a church and school and experience Africa firsthand were rocked by blasts that injured six of them, a pastor said Monday.
The Rev. Kathleen Kind of the Christ Community Church in Selinsgrove said none of the injuries appeared to be life-threatening, though one missionary suffered serious leg injuries in the explosions Sunday.
"The nature of the trip was to work with our sister congregation in Uganda," said Kind, who added that the missionaries have been in contact with their families. "The community of faith here is actively praying for these persons."
Three of the injured were from her church and the other three were from other churches in the area, she said. They were part of a group of about 14 who had traveled to Uganda for a mission last month and were supposed to have returned Monday.
Kind said the group on the missionary trip has also set up a website - uganda2010.editme.com - updating the conditions of the injured.
According to a website, the injured missionaries include Emily Kerstetter, Joanne Kerstetter, Kris Sledge, Pam Kramer and Thomas Kramer.
The website also said it had received confirmation that the pastor of Bwaise Pentecostal Church and the LifeCare School, Peter Mutabazi, had been killed.
Thomas Kramer, 14, said that at first he thought the explosion was a firework, and then discovered his leg was bleeding. He told Reuters TV that if he were sitting two seats to his left "I would have lost my life, because our friend Becky, she is from Uganda, she didn't make it."
Sledge, 18, said from his hospital bed in Uganda that he was "just glad to be alive."
The deadliest attack occurred at a rugby club as people watched the World Cup final between Spain and the Netherlands on a large-screen TV outdoors. The second blast hit at an Ethiopian restaurant.
One of the members of the missionary team, Lori Ssebulime, told The Associated Press the members had arrived early at the restaurant for dinner and to get good seats to view the match.
"We got there early so we could be near the screen," she told AP. "The blast happened. It was total chaos. I fell over backwards. Everything was gray."
She said she scrambled around the bodies and found Emily Kerstetter, 16, and got her inside a minivan.
"Emily was rolling around in a pool of blood screaming," she said. "Five minutes before it went off, Emily said she was going to cry so hard because she didn't want to leave. She wanted to stay the rest of the summer here."
Ssebulime, who was identified on the web site as "shaken but not seriously injured," said the explosions have shattered her sense of well-being.
"I love Uganda. I can't believe it happened here," she said. "I am totally in shock. I feel like I'm in a dream floating."