Suffolk County police used a robot to investigate a “suspicious” backpack left at a Bay Shore Best Buy Monday night — but found only a load of school books inside.

A police spokeswoman said the store was evacuated after an employee called police about the bag at 8:04 p.m. The department’s Emergency Services Unit, a SWAT-like team, secured the area and moved in with a portable X-ray device. When an initial scan suggested the contents did not appear to be an explosive device, officers used a robot to unzip the bag. They found several spiral notebooks.

Police said somebody loading merchandise into their car may have left the bag.

The spokeswoman said the ESU handled the incident the same way it would any call about a suspicious item.

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“It was handled the way all suspicious items are handled — carefully until deemed safe,” she wrote in an email.

Nobody answered a phone call to Best Buy Monday night, and police did not know how many people were evacuated.