I did not realize that CNN reported all that info - sourcing to state and fed (probably because there's a self-imposed prohibition against watching CNN in my home).
Taken at face value, that report explains the caution LE is taking regarding the release of additonal information. How do you issue a composite sketch when different witnesses are descibing different members of the cell. Take one cell member out - and you're still left with 3-4 who will soon thereafter strike again and "vindicate" the member in custody - eroding public confidence in LE at the same time. That would be a nightmasre scenario.
We should know A LOT more by the end of the day. If there's no attack, bet your bottom dollar, they have the cell under tight surveillance. I'm just not convinced a terrorist cell would pack bags and disappear. Wouldn't be the first time I was flat wrong, though.