CREVE COEUR • A bomb scare that closed Interstate 270 near Mercy Hospital was triggered after an emergency room worker saw what appeared to be a suspicious device inside a patient’s bags, police said.

The apparent device involved cellphones wired together, according to St. Louis Police Capt. Mary Warnecke, speaking for the St. Louis Regional Bomb and Arson Unit. The employee who spotted the items took them outside the hospital.

Using its bomb-grabbing robot on wheels, the squad X-rayed the first bag on the hospital’s helicopter landing pad, police said.

They chose to “disrupt” that bag as a precaution. Police would not say how they disrupted the device, but a boom was heard by nearby reporters.

Whatever the bag contained, it was not an explosive device, police said.

The second bag contained clothes and tennis balls. No explosive device was found in it, either.

The drama closed I-270 for nearly three hours. Lanes reopened after 2 p.m.