The Manchester suicide bomber who killed 22 people at a concert venue packed with children was part of a network, the city's chief of police said on Wednesday as troops were deployed across Britain to help prevent further attacks.
Police made three new arrests and searched an address in central Manchester in what police chief Ian Hopkins described as a fast-moving investigation.
"I think it's very clear that this is a network that we are investigating," Hopkins told reporters outside Manchester police headquarters.
"And as I've said, it continues at a pace. There's extensive investigations going on and activity taking place across Greater Manchester as we speak."