Four in French police custody for planning an attack: source

PARIS (Reuters) - French authorities put four members of a family in police custody on Wednesday as part of a preliminary investigation in connection with a plot to carry out an attack, a judicial source said. The four were arrested in the Clichy-sous-Bois suburb, east of the capital. Bomb-making materials, including acetone and sulphuric acid, which can be used to make explosives, were found in a building in the neighborhood in January. DNA traces from the objects led police to the suspects, who were arrested on Tuesday, the source said. France is under heightened alert following a spate of attacks by Islamist militants in several cities that has killed around 230 people since January 2015. (Reporting by Simon Carraud; Writing by Bate Felix; Editing by Jonathan Oatis)