Whitehall announced an internal investigation is currently unfolding in MI5 for the way Abedi’s radicalization warnings were handled, the BBC reports.

The investigation was opened after more information was released in the press that MI5 was warned by several people about the radicalization of Salman Abedi, the young man who installed chaos at the Manchester Arena killing 22 a week ago.

The MI5 leadership has launched an investigation into how Abedi’s warnings have been dealt with and also prepares a report for ministers and those monitoring the work of the service.

A Whitehall official said Abedi was a person of interest, whose risk was classified as being “under review” by security and partner services.

According to BBC, when Salman Abedi attended Manchester College courses, two people called for anti-terrorism to announce that he was radicalized.

14 people are in police custody nearly a week after the Manchester Arena attack, and Interior Minister Amber Rudd said it is possible that some of the network members of Salman Abedi were still at large.

At least 22 people have died and more than 100 have been injured as a result of explosions that occurred Monday night at the end of a concert by Ariana Grande on the Manchester Arena, Europe’s largest concert hall.

The bomb was triggered in the foyer of the building.

Physicians who intervened at the scene described the status of the victims, mostly children and adolescents, being hit by shrapnel.

This is Britain’s bloodiest attack after July 7, 2005, when 52 people died after a series of blasts hit the London transport system.