San Francisco, June 20 : iPhone Crash Detection feature caused chaos on the first day of the Bonnaroo festival in the US on June 15 by placing multiple accidental 911 (emergency services number) calls. Bonnaroo is a four-day music and art festival. According to Manchester police, the calls were caused by a malfunction with iPhone's feature, which automatically alerts the police if the phone detects a crash, reports New York Post. "Bonnaroo Guests: MPD (Manchester police department) has responded to multiple accidental 911 calls at Bonnaroo. It's likely that these calls are a result of 'Crash Detection Mode', a new feature on Apple iPhones. Please be mindful and consider deactivating this feature on your phone until Bonnaroo concludes," Manchester Police tweeted. According to Apple, when users' iPhone detects a severe car crash, it will display an alert and will automatically initiate an emergency phone call after 20 seconds, unless they cancel. The Bonnaroo organisers also used Twitter to spread the word, saying, "Let's work as a team to resolve this!" They then demonstrated how to disable "Crash Detection Mode" in the iPhone settings. "You can take action by going Settings>Emergency SOS and deactivating the 'crash' feature," the team tweeted. However, no crashes were reported during the four-day music festival. In January, false alarms by the iPhone Crash Detection feature caused problems in Japan, with fire departments near skiing areas getting more emergency call-outs than usual because of the automated calls. /IANS