How to get a collection of selected cells in datagridview

My code currently allows a user to select an item at ago from a list of items in datagrid view.

I would want to change it so that it allows the user to select more than one item to be processed. i.e it now allows user to generate a report for one selected employee but i want to change that so that a user can generate more than one employee`s report at once

Here is my current source code

private void dgvPrintEmp_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
//added
this.Clear_PrintEmp();
if (e.RowIndex < 0)
return;
this.mStudId = Convert.ToInt32(this.dgvPrintEmp.Rows[e.RowIndex].Cells["empid_PrintEmp"].FormattedValue);
this.lblEmpPrintEmp.Text = this.dgvPrintEmp.Rows[e.RowIndex].Cells["Empname_PrintEmp"].FormattedValue.ToString();
this.btnPrintEmp.Enabled = true;
}