Gellar 42, said in an Instagram post Wednesday that she had an unexpected run-in with Blair, her Cruel Intentions co-star, after evacuating her home in the Los Angeles area.
Gellar shared a photo of herself posing with Blair, 47, in a hotel lobby. The pair both wear sunglasses and casual outfits.
"I left my house on Monday am at 3 am when we were evacuated, with the clothes on my back (since been washed don't worry) and my family. I'm definitely scared and emotional, but then I get a surprise of @selmablair and now I can't stop smiling," Gellar captioned the post.
"These moments remind me to be grateful for all the blessings I have, and Selma you are certainly one of them. Once again thank you to the @losangelesfiredepartment for all you do. We owe you so much," she added.
Blair posted the same picture on her own account.
"#womancrushwednesday forever. #sarahmichellegellar #bff always there when I most need her," she wrote.
Wildfires have been raging throughout Southern California for nearly three weeks. Firefighters fought Wednesday to protect the Ronald Reagan Presidential Library and museum from the Easy Fire in Simi Valley, Calif.
Blair was diagnosed with multiple sclerosis in August 2018 and has been public about her experience with the disease. She wrote in August about her struggle with insomnia.