The finale of Grey's Anatomy season 10 will be airing tonight, with viewers bidding farewell to beloved character Dr. Cristina Yang, played by actress Sandra Oh.

Oh will be leaving the hit medical drama series after ten years, and fans will find it hard to see the veteran character depart from show.

Millions of viewers will be tuning in tonight watch how Cristina Yang will exit the show, as there is still no clue of how she will leave.

The title of the finale episode is "Fear (of the Unknown" and has been described by some as "explosive."

The promo for the finale episode teases fans, which states "The goodbye you never expected." The synopsis is as follows: "In the 10th season finale, Cristina's coworkers give her a fond send-off. Meanwhile, a possible terrorist act occurs in Seattle and leads to pandemonium at the hospital; Meredith makes a life-altering choice; and a doctor gets alarming news."

Earlier this month, fans saw the return of Dr. Preston Burke, Yang's former lover, but it was made well clear that the two would not get back together as both have moved with their lives. But Burke did give a job offer to Yang which she could not refuse, and she will be well on her way to Switzerland.

Fans fear that Oh's character could depart by being killed off, but hopefully that will not be happening.

The sneak peek preview also hints at a nearby terrorist attack sending victims to the care of Grey Sloan Memorial.

Actress Caterina Scorsone, who plays Amelia, told TV Line: "It's going to be 'all hands on deck,' absolutely. It's chaos. It's Shondaland!"

After tonight's Grey's Anatomy season finale, Sandra Oh will be starring in a play, "Death and the Maiden" by Ariel Dorfman, which will be running from June 13 to July 13.

"The play was starting to help me think about life beyond or past 'Grey's,'" Oh told Calgary Herald. "When I was making the decision, it was not a quick, snap decision at all. It took a long time. I gave myself, honestly, two years to process it. The first thing came when I said, 'OK, yes, I'm going to do this play.' And it's like, you say you're going to do something in two years from now, you can say no.

"But I basically stuck to it just knowing that I had a goal in the forefront."

Be sure to catch Sandra Oh's farewell in the season 10 finale of Grey's Anatomy on ABC at 9 p.m. Thursday.

The season 10 finale episode will also be available to view online via live stream on ABC.