peaking at a ferry christening ceremony in Szczecin on Wednesday, Tusk said the country’s history was made up of "joyful days and difficult days," but that on 11 November "all hearts are white and red," the colours of the Polish flag.
He sent greetings to those attending Independence Day ceremonies in Warsaw, and to the residents of Kraków and of Ostrowiec Świętokrzyski, where Saturday’s attacker came from.
He said both communities were going through difficult days.
Six people were killed and 16 injured in the attack.
Those hurt included two police officers and the attacker, who died in hospital on Monday.
Tusk singled out officers Artur Morański and Jakub Kulik, who stopped the attacker on 7 November.
"All of Poland is with you today," he said.
"You are our heroes, who restored our faith in humanity."
The ceremony in Szczecin marked the christening of a new ferry, Bursztyn Unity, which Tusk had called "a beautiful gift for all Poles" on the anniversary of independence.
The ship was built by the Gdańsk Repair Shipyard to carry passengers and wheeled cargo.
Transport Minister Dariusz Klimczak, who also attended the ceremony, said: "This is a new Polish ship – a Polish project, built by Polish engineers at a Polish shipyard, and operated by a Polish shipowner.
"There is no better day than Independence Day to raise the Polish flag on a new Polish vessel," he added.
The ferry will sail under the Polish flag and be run by a domestic operator, with regular crossings between Świnoujście and Ystad in Sweden due to start on 18 November.
(ał)
Source: PAP