Bettendorf police shut down the BP gasoline station at the corner of 18th Street and Spruce Hills Drive late Thursday afternoon in connection with an investigation that police could offer no details about.
Drivers during the rush-hour traffic watched police work and asked bystanders what was happening.
Several police vehicles blocked the entrance to the station.
Police Chief Phil Redington said there had not been a robbery and that no one was in any danger at any time. He said he could not disclose the nature of the investigation.
A white Ford 4x4 pickup was at one of the gasoline pumps. An officer took a police dog around the vehicle to sniff it for contraband.
Redington said he hoped to be able to release information today.