Stock market measures in the U.S.fell Tuesday after strong gains in the first hours of trading.The Dow Jones Industrial Average indexclosed Tuesday with a loss of more than one percent,after rising earlier in the day by almost 3 percent.The volatility in stock prices came after China's stock exchangesdropped sharply for the second day.In Shanghai, the stock index fell almost 8 percent,after Monday's drop of 8.5 percent.Investors blame concerns over an economic slowdown in Chinaand its effects on growth around the world.France announced Tuesday it has launched a terrorism investigationinto last week's armed attackon a train traveling between Amsterdam and Paris.French officials saidthey were investigating a Moroccan manfor "attempted murderin connection with a terrorist enterprise."The suspected gunman, Ayoub El-Khazzani,watched a radical Islamist video on his phonemoments before he walked through the trainwith several guns and ammunition.Officials are expected to file charges against the man by Tuesday night.The gunman was stopped by three Americans and a British citizen.Another man, a Franco-American tried to take away the gunman's weapon.He was shot and remains in the hospital.The Islamic State group has posted pictures on the Internet that, it says,show the destruction of a 2,000-year-old temple in Palmyra, Syria.The ancient city is a UNESCO World Heritage Site.In some of the pictures,several men are carrying barrels into the temple.They put down the containers connected by blue wireson columns that support the structure.Other photos show a cloud of smokeand pieces of rock that appear to show the results of an explosion.UNESCO calls the temple's destruction a war crime.UNESCO is the United Nations agencyfor culture, science and education.The Islamic State group seized Palmyra in May.