Washington - US tech leaders and celebrities have joined a call for an "Internet moment of silence" on Friday to remember the victims of last week's massacre of 26 people at a Connecticut elementary school.Twitter founder Jack Dorsey, television host Ryan Seacrest and singer Britney Spears were among the leaders of the "Stand with Sandy Hook" campaign launched online at causes.com.They called for backers to halt online activity at 13:30 GMT to reflect on and seek action to prevent a recurrence of the tragedy."Please join in a national moment of silence in honour of the Sandy Hook victims called for by Connecticut Governor Dannel Malloy," the web page said.The web page also includes a "badge" which can be placed on blogs or sites to show support."In the coming weeks and months, we must come together around common-sense solutions that will prevent the gun violence that has become all too frequent in communities across the country," the statement said."2013 is the year to take meaningful action; observing this moment of silence on Friday, we can signal our resolve to stop senseless deaths like these from happening again."As of Thursday, more than 120 000 people had taken the pledge and 474 000 liked the action on Facebook.Others backing the effort include Salesforce.com chief Marc Benioff, tech investor Sean Parker, former American football star Joe Montana and actress Goldie Hawn.The massacre shocked the country, and may have shifted the political debate on firearms in US society after years of gun lobby ascendancy. The shooter, Adam Lanza, also killed his mother, and then took his own life.