By Ole Mikkelsen and Sabina Zawadzki Copenhagen (Reuters) - Tens of thousands of Danes gathered at torch-lit memorials around the country on Monday, commemorating victims of deadly attacks on a synagogue and an event promoting free speech that shocked a nation proud of its record of safety and openness. Singing John Len**n's Imagine, Defiant Danes promised to uphold their trademark open society and showed solidarity with the country's Muslim mi**rity after reports the gunman was a Dane with Palestinian roots and a passion for Islamist issues. The 22-year-old gunman opened fire on a cafe in hosting a free speech debate on Saturday, killing one, and attacked a synagogue, killing a guard. He was later killed in a shootout with police in his neighborhood of **rrebro, a largely immigrant part of the city with a reputation for gang violence.