CONFIRMATION MESSAGE WHILE DELETING A ROW FROM GRIDVIEW

<asp:TemplateField HeaderText="DELETE" ShowHeader="False">
                        <ItemTemplate>
                        <span onclick="return confirm('Are you sure to Delete?')">
                            <asp:Button ID="Button1" runat="server" CausesValidation="False"
                                CommandName="Delete" Text="Delete" />
                        </ItemTemplate>
</asp:TemplateField>