A man holds his head in his hands as he lays flowers in front of the Carillon cafe, in Paris, Saturday, Nov.14, 2015. French President Francois Hollande vowed to attack Islamic State without mercy as the jihadist group admitted responsibility Saturday for orchestrating the deadliest attacks inflicted on France since World War II. (AP Photo/Thibault Camus)

French president vows to punish Islamic State group for Paris attacks that kill 129

Grief, alarm and resolve spread across Europe as officials raced to piece together information on the attackers.