People lay flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People lay flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

An electronic screen in St. Petersburg metro displays an image mourning for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People lay flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

A man lays flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

This photo taken on March 23, 2024 shows flowers and candles laid by people to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia. (Photo by Irina Motina/Xinhua)

This photo taken on March 23, 2024 shows flowers and candles laid by people to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia. (Photo by Irina Motina/Xinhua)

An electronic screen shows an image mourning for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

A woman lays flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People lay flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People walk past an electronic screen showing an image mourning for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People mourn for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People lay flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

People mourn for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

A woman lays flowers to commemorate victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)

An electronic screen in St. Petersburg metro displays an image mourning for victims of Moscow terrorist attack in St. Petersburg, Russia, March 23, 2024. (Photo by Irina Motina/Xinhua)