"Note that Trump’s coronavirus team is all male, all old, and all white," King tweeted during Trump's press conference. The president was in the middle of discussing the pandemic and his declaration of a national emergency.
Behind him stood several members of his coronavirus task force, including Centers for Medicare and Medicaid Administrator Seema Verma, who is neither male nor white.
Just minutes after King's tweet, Dr. Deborah Birx took the podium. Birx, a world-renowned medical expert, was named the White House's coronavirus response coordinator.
She has worked extensively in the global fight against HIV/AIDS -- both as the State Department's U.S. global AIDS coordinator and as the U.S. special representative for global health diplomacy.
Verma also took the podium moments later.
"Whoop, there's a woman there! My bad," King tweeted. In a follow-up tweet, he added: "Quite the parade of white men in ties, eh? the lady with the shawl looks so great compared to the rest of those bozos."
Surgeon General Dr. Jerome Adams and Housing and Urban Development Secretary Dr. Ben Carson are also prominent members of Trump's response team.
Others blasted the "It" author for jumping the gun with his tweet.
"Social justice and intersectionality will kill us all. This is what Stephen King tweets during a public health emergency," radio host Jason Rantz said.
"Good God shut up," Daily Wire writer Jessica Fletcher reacted.
This wasn't the first time a high-profile Trump critic made an incorrect assumption about Trump's associates. Former Sen. Claire McCaskill received a wave of backlash after she appeared to single Carson out for his race.
"One of these things is not like the others. Hint: they made him squat in the aisle so he was visible," McCaskill, now a political analyst for NBC News and MSNBC, tweeted alongside a photo of Carson on an airplane with other Trump supporters.
Katrina Pierson, a black woman who serves as a senior adviser for Trump's campaign, tweeted: "Only a closet racist would make such an incredibly stupid and non factual [sic] observation. There were several 'things' on that plane. TWO OTHERS IN THAT ROW! You’re trying too hard, but don’t worry... You’ll see us soon in a town near you."
Fox News' Brie Stimson contributed to this report.