Fans of Thirty Seconds to Mars were treated to a surprise performance by front man - Jared Leto.

Video shows crowds of excited fans gathering around Jared Leto for a sing-a-long of one of the bands biggest hits, The Kill.

Long-time fan Isabela Avellar, 30, was able to attend after spotting a post on Instagram calling on fans to gather in London's Piccadilly Circus for a special appearance.

Isabela, who lives in London but is originally from Brazil, said:

"I was going for a walk in Camden Town on Sunday when I saw Jared's stories saying he would be at Piccadilly."

"Lots of his fans, including me, raced down there to wait for him."

"When I saw him I didn't know how to act, my heart almost came out of my mouth."

"I just couldn't believe that it was really happening-It was magical!"

"Everyone was very happy to see him there with us. I think, we fans, really like it when our idol gives us that kind of attention. We feel closer."

Thirty Seconds to Mars are currently on tour with several dates scheduled throughout June across the UK.