This photo taken in Moscow, Russia on March 23, 2024 shows screens displaying Russian President Vladimir Putin speaking in a televised address to the nation. (Xinhua/Cao Yang)

MOSCOW, March 23 (Xinhua) -- Russian President Vladimir Putin said Saturday all four gunmen in the Moscow terrorist attack were arrested.

Putin, addressing the nation, said that all those responsible for the deadly attack would be punished. He also ordered that Sunday will be a nationwide day of mourning.

A deadly shooting at a concert hall in suburban Moscow Friday killed at least 143 people and injured over 100, local authorities said.