Belgium's leaders, including the premier and royal heir apparent, led a crowd of thousands who packed the Liege city square Tuesday to remember the victims of last week's shooting spree.

The wistful tune of the Irish ballad "Danny Boy" played on a lone trumpet echoed across the square as a crowd of 2,000 to 3,000 fell silent, seven days to the hour after last Tuesday's deadly attack.

Three youngsters -- two teenage boys and a 17-month baby -- and a 75-year-old woman were killed when a former convict armed with grenades opened fire on a crowd of Christmas shoppers and children just out of school.

Belgium's Prince Philippe and Princess Mathilde, along with new Prime Minister Elio Di Rupo, laid wreaths of white roses and paid condolences to the families of the victims at the silent homage.

A large sign hung on a bus shelter shattered by the gunman's grenades and now turned into a memorial, read "Never Again!"

Around 10 people remain in hospital, one in critical condition, after Nordine Amrani, a 33-year-old parolee with a lengthy criminal record who appeared anxious that he might face new charges, went on the rampage last Tuesday before turning a gun on himself.

Police later found the body of a murdered cleaning woman in her forties lying in a shed that Amrani used to stash cannabis and arms.