Twin teenage girls who are thought to have travelled to Syria are "deeply religious Muslims", police understand.
It is understood an older brother has joined the extremist militant group Islamic State of Iraq and the Levant (Isis), and one line of inquiry is that the girls may have flown out to join him.
The girls, from a large Somalian family, flew from Manchester International Airport to Turkey which borders Syria where the civil war involving Muslim militants is raging.
Greater Manchester Police said the pair had been in contact with relatives since their departure.
More top news
Police carried out a "proactive" operation after receiving reports that other concerts by the band had seen lots of mobile phone thefts.
The child died on her injuries and another 14-year-old girl was injured after the buggy they were travelling in was involved in a car crash.
Cloud thickening from the west throughout the day. Rain in northwest later.