09/02/2009 AT 12:00 AM EDT
Seattle Grace is losing another doctor -- at least temporarily. Katherine Heigl
, 30, is taking a leave of absence from Grey's Anatomy
to film a new movie, the romantic comedy Life as We Know It
An ABC rep cannot confirm the exact length of time she will be out of pocket -- EW.com
is reporting a 5-episode hiatus -- but tells PEOPLE, "Katherine is taking time off to film a movie. The producers at Grey's
have accommodated past things like that before. It's a cast of 13 and it is a true ensemble so the show is mindful of other commitments."
Heigl's departure is set to begin this month, last into November and will be explained on screen, EW
reports. Meanwhile, fellow castmate Ellen Pompeo
is due to give birth to her first child in October and is expected to take maternity leave around the same time -- an overlap that's "all being worked out," the rep tells PEOPLE.
The rep also notes that none of these events were surprises for the show. "Shonda Rhimes
has had plans in place for a very long time." But don't expect producers to reveal how they will explain where Izzie is during Katherine's hiatus.
In related casting news, show producers announced that three new characters will join the cast in recurring roles. They will be played by Nora Zehetner
, Robert Baker
, and Jesse Williams
In June, T.R. Knight announced he was leaving
the ABC drama after months of speculation. --Brian Orloff and Cynthia Wang