Gunmen Kill American Teacher in Benghazi BENGHAZI, Libya - Unidentified men gunned down an American chemistry teacher here on Thursday morning as he went for a jog outside his home, according to Libyan security officials and the director of the teacher's school. A colleague identified the teacher as Ronnie Smith, 33, of Texas. Libyan security officials said they had not yet determined a motive for the killing, which came during a weekslong surge of assassinations and armed clashes in cities across the country. The State Department confirmed that an American citizen had been shot and killed in Benghazi, without providing further details. Many foreigners long ago fled Benghazi, the birthplace of the uprising against Col. Muammar el-Qaddafi in 2011 and now a symbol of Libya's growing anarchy. There has been a string of extremist attacks on diplomats and other foreigners, most notably the September 2012 killing of the American ambassador, J. Christopher Stevens. Assassinations of security officers or former Qaddafi officials are reported almost daily. The city's unaccountable militias are the biggest challenge to the government's control. Last week, at least nine people were killed as a militia linked to the killing of Mr. Stevens, Ansar al-Shariah, battled a local military unit. On Thursday, at least four security officials were assassinated in Benghazi. Despite all the violence, Mr. Smith, who had been in Benghazi for 13 months, "never thought for a moment he would be targeted," said Adel Mansouri, the director of the International School in Benghazi, where Mr. Smith taught chemistry to secondary school students. On Thursday morning, Mr. Mansouri said, he received a call from Mr. Smith's landlord telling him about the shooting, and went to identify the teacher's body, which was lying outside his house in an upscale neighborhood near Dubai Street. "He liked it there," Mr. Mansouri said. He felt very safe. He jogged every day. Mr. Smith lived in Benghazi with his wife and young son, who were in the United States at the time of the attack. Mr. Mansouri called Mr. Smith the most popular teacher in the school. He was active on Twitter, where he interacted with students, kept what amounted to a diary of his life in Benghazi and called himself "Libya's Best Friend." Several entries voiced frustration with the city and its residents. At other times, he praised the place. "There's one thing Libyans are good at: making foreigners feel like family," he wrote on Oct. 20. In several entries, he poked fun at the militants. On Oct. 24, he wrote: "Where's Ansar Al-Sharia when you need them? Someone make a call and tell them boys and girls making out here. In another entry, he called Libyan Islamists "losers." On Nov. 25, the day members of Ansar al-Shariah were driven from their base in Benghazi after armed clashes, Mr. Smith wrote: "More like Ansar Al-see ya!" A man reached by telephone in Michigan who identified himself as Mr. Smith's brother-in-law declined to comment on his death. "If you could give us a couple of days, that would be great," said the man, who identified himself only as Jason. We just found out about an hour ago. The University of Texas at Austin, where Mr. Smith earned a master's degree in chemistry in 2006, released a statement calling his death "a tragedy for the campus and our nation." Mr. Smith's students in Benghazi posted numerous recollections online on Thursday. "He was one of the very few who didn't leave Libya when all the others did," one girl wrote. They also posted pictures, including one of his wedding, and another of him standing in a yard with his wife and son. Another appeared to show him after he was shot, still wearing running clothes and his earphones, with blood pooling at his side. Is this a robbery, or terrorism? We just don't know," Mr. Mansouri said. Suliman Ali Zway reported from Benghazi, and Kareem Fahim from Cairo. Rick Gladstone contributed reporting from New York, and Manny Fernandez from Houston.