How to Get data on double click in Gridview Rows

protected void Gridview1_SelectedIndexChanged(object sender, EventArgs e)
    {
       string firstCellText  = Gridview1.SelectedRow.Cells[1].Text;
       string secondCellText  = Gridview1.SelectedRow.Cells[2].Text;
       string thirdCellText  = Gridview1.SelectedRow.Cells[3].Text;            
       .........
       //continue till your cell number like above
    }