INA 212(a)(3)(A)(i) renders inadmissible any alien who the consular or immigration officer knows or has reason to believe seeks to enter the United States to engage solely, principally, or incidentally in any activity that violates any United States law relating to espionage or sabotage. If you and your friends were rejected on the same day, odds are it's because of the outcome of the same investigation.
We don't know what inspired the finding. It would be sensible for you to consult an immigration lawyer.

