What kind were they? I think the one towards the end was an Mil Mi6? Maybe?
Moving thread from General Questions to Cafe Society.
A lot of web sites say Mil Mi-26.
The Die Hard Wiki also mentions a Hind F (Mil Mi-24).
The Hind is in the earlier scene when it is shooting up the hotel. The helicopter at the end is a Halo (Mi-26). I know the Hind was shot using both live action and CGI. Probably some CGI at the end too.