SAN JOSE, Calif. --A 19-year-old Marine from San Jose was killed during a tour of service in Afghanistan on Wednesday, the U.S. Department of Defense announced Thursday. Lance Cpl. Ardenjoseph A. Buenagua - known more familiarly to friends and family as Arden - died while conducting combat operations in the country's Helmand province. Buenagua belonged to the 1st Combat Engineer Battalion, 1st Marine Division, I Marine Expeditionary Force based out of Camp Pendleton in Southern California. In the days leading up to his late September deployment, Buenagua used his iPhone to post frequent updates to his Facebook page, including his last post from Sept. 30 announcing his arrival in Afghanistan. Days before, on Sept. 24, Buenagua wrote of insomnia spurred by excitement for his first tour of duty and trip out of the country, writing, "can't wait to get a (peek) at the rest of the world!" Buenagua's mother, Marivic Ayuson Trinidad, lavished constant support on her son's page and responded to his last post, praying for his safety and encouraging him to do the same. "Pray, pray, and pray always," she wrote on his page on Sept. 30, adding "we're praying for ur SAFETY." According to networks Buenagua listed on his page, he graduated from Piedmont Hills High in 2009 and also attended Independence High School. Former classmates, like Alex Rivera, remembered Buenagua for his laid-back personality and ambition. "I met this dude my (sophomore) year in world history," Rivera posted on his own Facebook page Wednesday night. "He was a chilled laid back kinda guy but really smart with great ambition." Casting a somber shadow over the Thanksgiving holiday, others such as Laura Choo publicly expressed their shock and made their fondness for Buenagua known on the Web. "Arden Joseph Buenagua, it's still unreal to me & everyone else," Choo posted on Thursday. "thanks for the memories, love you. Rest In Paradise."