Carl XVI Gustaf

The attack has sent shockwaves through the nation, with King Carl XVI Gustaf on Wednesday saying: "All of Sweden is mourning."

It's also worth noting that the three current monarchs are all related: Norway's King Harald V and Sweden's Carl XVI Gustaf are Margrethe's second and first cousins respectively.

Neither has Sweden’s 77-year-old King Carl XVI Gustaf, who last year celebrated 50 years on the throne.

In September, Harald attended celebrations in Stockholm marking the 50th anniversary of Sweden’s King Carl XVI Gustaf’s accession to the throne.

In Sweden, climate activists gathered in front of Parliament, just next to the Royal Palace where Sweden’s King Carl XVI Gustaf was celebrating his 50th anniversary on the throne.