CBS medical drama Code Black will not return for a fourth season. Creator/showrunner Michael Seitzman revealed the news in a note to fans early Thursday on Twitter.

“The sad news came today that we were cancelled,” Seitzman wrote. “It’s been a true joy to make this show and watch your response every week. Thank you for all of your passion. Truly, our best episodes have yet to air. We hope you’ll watch and enjoy them. We made them for you.”

The series returned April 25 to soft numbers (0.7 rating in 18-49 demo, 5.56 million total viewers), with its Season 3 premiere down 33% compared with last season’s debut. It came down to the wire last year, with the show getting a last-minute Season 3 renewal, as it did for Season 2. Because of the late start, the network this year postponed the renewal decision until after the upfronts.

The decision not to renew for a fourth season was not a surprise. Seitzman wrote that the season finale was written as a series ender. “We always suspected this would be the last season. We wrote it to end that way,” he tweeted.

Created by Seitzman, Code Black took place in the busiest, most notorious ER in the nation, where the staggering influx of patients outweighed the limited resources available to the doctors and nurses whose job is to treat them all – creating a condition known as Code Black.

Marcia Gay Harden starred along with Boris Kodjoe, Harry Ford, Benjamin Hollingsworth, William Allen Young, Emily Tyra, Noah Gray-Cabey, Emily Alyn Lind and Moon Bloodgood, along with Luis Guzmán and Rob Lowe.

The series was produced by ABC Television Studios in association with CBS Television Studios. Seitzman executive produced with David Marshall Grant, Rob Bowman, Marti Noxon, Linda Goldstein Knowlton, Ryan McGarry and Mike Weiss.