Terror Attacks in London

I heard about the terror attacks in London while I was at work last night, but didn't remember until I got home this morning that our niece had flown to London from Boise on Tuesday. We haven't heard anything yet, but the family she was staying with lives in the suburbs, and we don't think they would have been heading into town during rush hour. Our prayers are with all those impacted by these cowardly attacks.
While it seems obvious that Islamic terrorists are the likely culprits, I was surprised to see this article that claims the British police "had received warnings of possible terror attacks in the city". It's not normally Al Qaeda's SOP to give out advanced warnings, although it could be that Scotland Yard had gotten warnings via surveillance or other such active intelligence-gathering methods. While first reports after something of this magnitude should always be taken with a grain of salt, if it turns out that a warning phone call went out in advance, this could point to some other terrorist group. I doubt it will, though...

Update 1530 07 July: It turns out that the "advanced warning" initial story was untrue; still, I expect we'll see threads over at DU for months or years claiming this as evidence of Israeli involvment in the bombings. On a personal note, my niece is fine; she was on her way in towards London, but they got turned around before they reached downtown.