People.com Celebrity Mariska Hargitay and Cara Delevingne Are the Latest 'Bad Blood' Stars to Join Taylor Swift on Tour Swift also brought Echosmith onstage during her Philadelphia tour stop By Lindsay Kimble Lindsay Kimble Lindsay Kimble is a Senior Digital News Editor and the Sports Editor for PEOPLE Digital. She's worked at PEOPLE for over seven years as a writer, reporter and editor across our Entertainment, Lifestyle and News teams, covering everything from the Super Bowl to the Met Gala. She's been nominated for the ASME NEXT Awards for Journalists Under 30, and previously wrote for Us Weekly while on staff at Wenner Media. People Editorial Guidelines Published on June 13, 2015 01:50 PM Share Tweet Pin Email Photo: Dimitrios Kambouris/Getty Taylor Swift has been regularly surprising 1989 world tour concertgoers with special guests, and her Friday show in Philadelphia was no exception. The singer, 25, was joined onstage by actress Mariska Hargitay and model pal Cara Delevingne during her stop at Philadelphia’s Lincoln Financial Field. Both Hargitay, 51, and Delevingne, 22, were featured in the star-studded and action-packed music video for Swift’s single “Bad Blood.” “Couldn’t even contain my happiness because @caradelevingne and @therealmariskahargitay surprised the crowd tonight,” Swift captioned an Instagram photo of the three posing onstage during the show. The stars danced and sang alongside Swift while she performed her hit single “Style.” “Justice and Mother Chucker at #1989TourPhilly,” said of another photo of the trio, referencing the women’s “Bad Blood” alter-egos. https://instagram.com/p/33H1ngjvJa/ Hargitay, who’s Law and Order: SVU character is Swift’s cat Olivia’s namesake, and Delevingne wore all black ensembles, while Swift stunned in a sequined silver fringe number. Pop band Echosmith also joined the songstress on stage Friday for a rendition of their hit single “Cool Kids.” https://instagram.com/p/33KIysjvLw/ Hargitay and Delevigne aren’t the first “Bad Blood” alums to join the tour. Swift brought out models Martha Hunt and Gigi Hadid during a 1989 May stop in Detroit. The blond beauties also strutted the stage with the singer during “Style.” How Taylor Swift’s 1989 Light-Up Bracelet Saved Lives