Grey’s Anatomy is known for dramatic finales, and Thursday’s Season 9 ender (Episode 24: “Perfect Storm) is no exception.

We already know that the fallout of Arizona cheating on Callie makes for an awkward moment and that Meredith goes into a painful labor, but there’s many more explosive moments ahead, too.

In the sneak peek clip below, things seem calm at first (hence the “calm before the storm”), but a domino effect starts as Matthew rushes in from the rain.

“What are you doing here?” April asks, bewildered. He explains, “The rig stalled out in the river that used to be Pike Street. I walked the rest of the way here,” clearly soaking wet. But ultimately, he just asks, “How can I help?

Owen instructs him to “grab some blankets!” and they all walk away. Seconds later as Callie and Bailey are strolling around with a patient, disaster hits.

They — along with Owen, Jackson, April, and Matthew — watch in horror as a bus soars through the air, skids across the street, flips over, and then sets on fire outside of the hospital. Is this yet another explosion? How many people must be saved inside the bus? We’ll have to wait and see the finale to find out, but one thing we know is that they all run to help.

Are you nervous or excited for the Season 9 finale? Sound off below!

The Season 9 finale of Grey’s Anatomy airs Thursday, May 16, 2013 at 9 p.m. ET/PT on ABC.

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Alyse Whitney is an editor at Wetpaint Entertainment. Follow her on Twitter @AlyseWhitney.