One of Europe's biggest music festivals in Denmark will sound a reflective first note Thursday, with American rocker Patti Smith commemorating a fatal crush in 2000, organisers said. Smith and her guitarist Lenny Kaye will open the festival in Roskilde, attended by some 75,000 people, remembering June 30, 2000, when nine young fans were trampled to death during the concert by US rock group Pearl Jam. Organisers have since put in place draconian security measures in the aim of avoiding any repetition of the accident that tarnished the image of the annual event, which is located west of the Danish capital Copenhagen. Nine trees have been planted near the scene in memory of the victims, which also serve as a reminder to festival-goers and staff to be careful while they enjoy the music on stage. Among the 150 rock, pop and techno groups performing at the round-the-clock four-day event, headliners at the 40th edition include US pop supremo Prince and British multi-genre band Gorillaz. 