DENVER —  Secret Service (search) officials say they had nothing to do with the removal of three people from one of President Bush's town hall meetings on Social Security (search).

But they are investigating the incident that allegedly happened last week in Denver. Three people who say they got tickets from the office of a Colorado Republican congressman say they were asked to leave as they tried to sit down. The three had arrived in a car sporting a "No Blood for Oil" bumper sticker.

A spokesman for the group Americans United (search) said the civil rights of the three people were violated. He also said it's disappointing that people are being screened at the gatherings and profiled in parking lots.