They've gone now

Mary has broken into an office building. She's sneaking around on the ninth floor. She's talking on the phone, but has to disconnect when two men come. She hides. The two men leave for another floor. After that, Mary calls the person she was talking to before she disconnected and explains:

Mary: Someone came, so I had to hide. I think they're gone now.

Mary: Someone came, so I had to hide. I think they've gone now.

Mary: Someone came, so I had to hide. I think they've left now.

Which of these are more natural? Is it "they've gone now"?