The FBI on Saturday arrested a pawnshop owner on a weapons charge after investigators said they found a note with his phone number and business address on one of the shooters in the deadly attack at a kosher market in Jersey City last week. Searches of Ahmed A-Hady’s home and store in Keyport, N.J., turned up a cache of ammunition and guns, including three “AR-15-style assault rifles” similar to one of the weapons used in the attack, according to a criminal complaint filed in federal court. Officials did not definitively link A-Hady to the shooting but said the searches were...