UK Police Nabs 15th Person in Manchester Bomb ProbeBritish police have arrested a 19-year-old man in connection with the Manchester bombing that killed 22 people last week. The arrest was made late Sunday during a raid in the Gorton area of Manchester on "suspicion of offences contrary to the terrorism act," the Greater Manchester police said in a statement. Earlier in the day, police arrested a 25-year-old and searched his property. Thirteen men remain in British custody in relation to the suicide bombing by Manchester native Salman Abedi, 22, in the lobby of Manchester Arena last Monday just after American pop singer Ariana Grande finished her concert.  A woman and teenage boy arrested by British police this week have been released without charges. Abedi's brother and father also were arrested in Libya last week where they are being held. A spokesman said that the brother, Hashim, was aware of Abedi's plans to attack. As the probe continues, Britain lowered its security threat level Saturday to "severe," Prime Minister Theresa May said. The level had been raised to "critical" — meaning another attack was thought to be imminent — after the concert bombing. The downgrade to "severe" means an attack still is considered highly likely.