Counter-terror police have carried out a controlled explosion as they searched a property in the Moss Side area of Manchester in connection with Monday's attack.
Locals reported hearing a "loud bang" in the area south of the city centre at around 1.45am on Thursday.
Eight men are in custody following a series of raids across Manchester, Wigan and Nuneaton, Warwickshire, following the attack by bomber Salman Abedi that claimed 22 lives.
A woman who was arrested in the Blackley area of Manchester on Wednesday has been released without charge.
Greater Manchester Police confirmed another search of an address had taken place, although there were no reports of any further arrests.
The force said in a statement: "This morning we have been carrying out searches at an address in the Moss Side area during which a controlled explosion took place.
"These searches are connected to Monday's attack on the Manchester Arena, but this is a fast, ongoing investigation and we are keeping an open mind at this stage."
The explosion was heard in the neighbouring areas of Rusholme and Fallowfield, with concerned locals taking to social media.
One wrote: "Does anyone know if the loud bang heard at 1:45amish this morning in/near Moss Side & Rusholme was an un/controlled explosion?"