In a Twitter thread, Bowser called her sister Mercia Bowser a “loving, daughter, sister, aunt, and friend” who worked “tirelessly for children, the elderly, and those with behavioral disorders until her retirement and beyond.”

“We’re grateful to the doctors and nurses at Washington Hospital Center, who heroically treated her for COVID-19 related pneumonia. We thank you for your kindness and will share how our family will honor Mercia, my only sister and oldest sibling, and her beautiful spirit in the coming days,” Bowser wrote.

“I ask that you continue to keep those who have been lost or impacted by the pandemic and those who are working so hard to protect us from it in your thoughts/prayers, and I respectfully request that my family and I are granted the time and space we need to mourn the loss of Mercia,” she added. 

My family and I are mourning the loss of my sister, Mercia Bowser, who passed away this morning due to complications related to COVID-19. Mercia was loved immensely and will be missed greatly, as she joins the legion of angels who have gone home too soon due to the pandemic.

— Muriel Bowser (@MurielBowser) February 24, 2021

Washington, D.C. recently reached more than 1,000 COVID-19 deaths, according to NBC Washington, and the country surpassed 500,000 deaths since last February. 

President Joe Biden held a ceremony at the White House on Tuesday to mark the grim milestone, imploring Americans to remember the lives lost.

“That’s how you heal — you have to remember. And it’s also important to do that as a nation. Those who have lost loved ones, here’s what I know: They’re never truly gone. They’ll always be part of your heart. I know what it’s like to not be there when it happens. I know what it’s like when you are there, holding their hands, looking in to their eyes as they slip away. That movie theater where you met. The morning coffee you shared together,” Biden said.