David Harewood
David Harewood took selfies with Grant Gustin, Candice Patton and Chris Wood on the set of the much-awaited musical crossover event between “The Flash” and “Supergirl.” Pictured: Harewood speaks onstage during the “Supergirl” panel discussion at the CBS portion of the 2015 Summer TCA Tour at The Beverly Hilton Hotel on Aug.10, 2015 in Beverly Hills, California. Getty Images/Frederick M. Brown

David Harewood recently took to Instagram to share a couple of behind-the-scenes photos from the set of the highly anticipated musical crossover event between “The Flash” and “Supergirl.”

The first picture shows Harewood smiling to the camera with Candice Patton standing behind him. The actor, who plays J’onn J’onzz on “Supergirl,” captioned the snapshot with Patton’s “The Flash” character name, “Iris West.” The photo was taken at the S.T.A.R. Labs set of “The Flash.”

In the second photo, Harewood is seen buddying up with “The Flash” actor Grant Gustin, along with Chris Wood, who plays Mon-El on “Supergirl.” As previously reported, Harewood and Wood will guest star in “The Flash” episode of the musical, but both actors won’t be singing.

The actors who have singing performances in the musical are Gustin, Melissa Benoist (Kara Danvers/Supergirl), Jesse L. Martin (Joe West), Carlos Valdes (Cisco Ramon/Vibe), Jeremy Jordan (Winn Schott), Victor Garber (Martin Stein/one half of Firestorm) and John Barrowman (Malcolm Merlyn).

Earlier this week, “Crazy Ex-Girlfriend” star and creator Rachel Bloom revealed to BuzzFeed News that she co-wrote a song for the musical.

“I immediately offered them my services [when I heard about the musical crossover],” Bloom wrote in a statement to the website. “As soon as they picked one of my song ideas, I hopped on the phone with my old ‘Robot Chicken’ boss Tom Root and we brainstormed and, based on that brainstorm, I wrote up the song ‘Super Friend.’ I am so excited to contribute more to the upward trend that is musicals in television and film. Music can be one of the most amazing and efficient forms of storytelling and character development. Also, it was really fun to write a comedy song for two superheroes.”

The Flash and Supergirl team up in the musical to take down the villain Music Meister (Darren Criss), who has the power to control people through song.

The musical will start at the end of “Supergirl’s” March 20 episode and will continue the next night in “The Flash’s” March 21 episode, where bulk of the action will take place. The second installment of the crossover, titled “Duet,” is directed by Dermott Downs.