DataGrid with Checkbox row

I have a datagrid that has a row of check boxes. I am having trouble figuring out how to create an event that handles the check box being selected or unselected. Does anyone know how to do this? Here is the column definition:

<asp:TemplateColumn HeaderText="Selected" ItemStyle-HorizontalAlign="Center" HeaderStyle-HorizontalAlign="Center">
<ItemTemplate>
<asp:CheckBox id="chkSelected" Checked="false" OnCheckedChanged="SelectedChanged" runat="server" />
</ItemTemplate>
</asp:TemplateColumn>