The 18-year-old killed two people and injured six more in the southwest Finnish city of Turku.
Monday's attack targeted worshippers from an institution with a proud history of fighting violent extremism.
Figures released by Mayor of London Sadiq Khan show as many as 20 incidents per day.
Khuram Butt and Rachid Redouane were "warned about their conduct" after wrestling in the water.
The divisions in the East End community have turned it into a flashpoint between white nationalists and radical Islamists.
Police have already named the other two attackers as Khuram Butt and Rachid Redouance.
After the third attack in less than three months, Prime Minister Theresa May said Thursday's election would go ahead.
The arrests were made in connection with Saturday's attack that killed seven.
"To prevent this extraordinary able young lady from not following her long-held desire would be too severe," said Judge Ian Pringle.
Israel's top medical association is preventing its members from taking part in the practice.
It is an old Russian strategy to conduct its attacks when the world is looking elsewhere.
Rob Lyon describes how he survived an attack in the heart of British democracy.
The actor was promoting his film 'Norman: The Moderate Rise and Tragic Fall of a New York Fixer.'
The obscure group has named itself after an attacker who killed three Israelis in the city in 2015.
The band also plan to record a song with Israeli and Palestinian artists.
The Palestinians will remain stateless after anti-settlements resolution, writes Israeli government minister Michael Oren.
Hilik Bar, deputy speaker of the Israeli parliament, outlines his vision for resolving the decades-long conflict.