Manchester police authorities are reporting that they executed arrest warrants on 3 individuals connected to Monday night's horrific bombing attack outside Manchester Arena.

The Greater Manchester Police aren't just yet releasing the names of the suspects that were taken into custody during several raids conducted on Wednesday, but are working under the suspicion that a larger conspiracy is behind the bombing.

"I think it's very clear that this is a network that we are investigating," Greater Manchester Police Chief, Ian Hopkins, said in a press conference.

The still ongoing police investigation has now brought in a total of 5 suspects connected to the case. Suicide bomber Salman Abedi's father was detained in Tripoli, Libya and his younger brother arrested on suspicion of having links to the Islamic State group.

Manchester police also set off a controlled explosion of what was believed to be another homemade explosive device.

In the wake of Prime Minister Theresa May's raising the country's threat level to "critical", increased militiary and police presence has been visible across Britain since Monday night's bombing.

As the wreckage clears, biritsh media confirmed an off-duty female officer was among the 22 victims.