"I always felt connected to her as we shared a very special experience in our lives together," Silverstone told PEOPLE on Sunday after Murphy's shocking death at age 32. "I feel love in my heart for her – and hope she is at peace. This is truly sad."
After their breakout 1995 hit, the actresses "didn't stay in close touch over the years," Silverstone says – a TV spinoff of Clueless starred other actresses – but their bond endured.
"I'm so saddened to hear this news," Silverstone says. "I loved working with Brittany. She was so talented, so warm, and so sweet."
Reporting by ELIZABETH LEONARD