UNB, Narayanganj :Militant outfit Islamic State (IS) has reportedly threatened to kill 20 members of Narayanganj Club.The threat was issued through a letter that reached the club on Monday afternoon.Club president Mahmud Hossain said he received a letter where the anonymous senders, claiming themselves as IS members, threatened to kill 20 members of the club as early as possible. He, however, did not elaborate but said they informed the police super of the matter.Contacted, officer-in-charge of Narayanganj Sadar Police Station Abdul Malek said he knows nothing about the letter.