Four people are in custody in connection with Monday’s deadly concert bombing, as British authorities continue to conduct “extensive” searches while investigating the “network” behind the attack.  “It is very clear that it is a network we are investigating,” Manchester police said on Wednesday.   British officials said they deployed nearly 1,000 troops at high-

profile sites in the country, some in London, instead of police. Manchester police said the increase in threat level gave the green light to deploy military support operation under the code name “Temperer.” Multiple law enforcement agencies swept through Manchester in a bid to head off a follow-up to the suicide bombing at an Ariana Grande concert that killed 22 other people. READ MORE