So i saw this movie about a boy and girl set of alien twins and i cant figure out what it was called.?

When i was younger i saw a movie about a boy and girl set of alien twins. The twins were apparently orphans but they were aliens I guess.. im not sure. Anyway the twins were blonde and the only scene of the movie i remember is the two kids hiding behind a wooden building while a spaceship came down to earth and then all these people appeared. If you know the name of this movie plz let me know. Thanks.