SANAA — An American photojournalist held by Al-Qaeda militants in Yemen has been killed in a failed rescue attempt, his sister said on Saturday. Lucy Somers said she and her father learned of her 33-year-old brother Luke Somers' death from FBI agents at 0500 GMT (12 a.m. EST) Saturday. “We ask that all of Luke's family members be allowed to mourn in peace,” Lucy Somers said from London. There was no immediate comment from security officials in Yemen's capital, Sanaa. A US Defense Department official said there was an attempted rescue on Friday to free Somers, but he said he had no information on its outcome. The official spoke on condition of anonymity as he wasn't authorized to brief journalists. Yemen's local Al-Qaeda branch, Al-Qaeda in the Arabian Peninsula, posted a video Thursday that showed Somers, threatening to kill him in three days if the United States didn't meet the group's demands, which weren't specified. He was kidnapped in September 2013 from Sanaa. The news of the failed rescue comes after a suspected US drone strike in Yemen killed nine alleged Al-Qaeda militants early on Saturday, a Yemeni security official said before news of Somers' death. The drone struck at dawn in Yemen's southern Shabwa province, hitting a suspected militant hideout, the official said. The official did not elaborate and spoke on condition of anonymity as he wasn't authorized to brief journalists. At least six suspected militants were killed in an airstrike in the same province last month. Later Saturday, tribal leaders said they saw helicopters flying over an area called Wadi Abdan in Shabwa province. American authorities rarely discuss their drone strike campaign in Yemen. The strikes are despised by many in Yemen due to civilian casualties, legitimizing for many the attacks on American interests. Before her brother's death, Lucy Somers released an online video describing him as a romantic who “always believes the best in people.” She ended with the plea: “Please let him live.” In a statement, Somers' father, Michael, also called his son “a good friend of Yemen and the Yemeni people” and asked for his safe release. In a statement Thursday, Pentagon press secretary Rear Adm. John Kirby acknowledged for the first time that a mysterious US raid last month had sought to rescue Somers but that he turned out not to be at the site. The US considers Yemen's Al-Qaeda branch to be the world's most dangerous arm of the group as it has been linked to several failed attacks on the US homeland. Kirby did not elaborate on the joint US-Yemeni operation to free Somers, saying details remained classified. However, officials have said the raid targeted a remote Al-Qaeda safe haven. Eight captives — including Yemenis, a Saudi and an Ethiopian — were freed. Somers, a Briton and four others had been moved days earlier. Somers was kidnapped in September 2013 as he left a supermarket in the Yemeni capital, Sanaa, said Fakhri Al-Arashi, chief editor of the National Yemen, where Somers worked as a copy editor and a freelance photographer during the 2011 uprising in Yemen. Somers, who was born in Britain, earned a bachelor's degree in creative writing while attending Beloit College in Wisconsin from 2004 through 2007. “He really wanted to understand the world,” said Shawn Gillen, an English professor and chairman of Beloit College's journalism program who had Gillen as a student. Fuad Al Kadas, who called Somers one of his best friends, said Somers spent time in Egypt before finding work in Yemen. Somers started teaching English at a Yemen school but quickly established himself as a one of the few foreign photographers in the country, he said. — AP