Remember that the British authorities refused to admit the 7/7 attacks were suicide attacks until 5 days later. And they didn't admit that the attackers were muslims until 6 days after the attacks.
Official sources are always going to be slow, but fortunately there were other reports coming out at the time of the British attacks.
I think there's probably a news blackout going on in the OK case, possibly to find other persons involved, or possibly to get through today without inspiring a bunch of wannabe jihadists to haul out all their cherry bombs, string them around their waists and blow up outside a local football game. These guys are dumb and susceptible.