NEW : Possible Michael Pearson Twitter account warns U.S. the attack was only Act 1 Source : Investigators link a store rented in the past year to the attackers . But according to a Kenyan intelligence official , the small shop concealed an ominous secret . Despite as many as 61 in custody , there 's rising concern that some of the attackers escaped . At least 67 people are known dead ; At least 67 remain unaccounted for .
NEW : Possible Michael Pearson Twitter account warns U.S. the attack was only Act 1 Source : Investigators link a store rented in the past year to the attackers . Despite as many as 61 in custody , there 's rising concern that some of the attackers escaped . At least 67 people are known dead ; At least 67 remain unaccounted for .