Updated

A reported exploding package and spray of white powder that sent emergency units rushing to a small-town post office turned out to be just the pop of a malfunctioning fluorescent light bulb, authorities said Friday.

The white powder that workers at the U.S. Post Office in Ranson saw was most likely smoke from the damaged bulb, said Ronald Fletcher, a firefighter with Citizens Fire Co. and the designated incident spokesman.

X-rays also revealed that a suspicious package in a storage locker contained only cookies, he said.

The scare Friday morning triggered an evacuation of the building and the temporary quarantine of 15 people inside a school bus. Hazardous materials and bomb experts, State Police units, fire crews and more responded to the scene at a strip mall.

The Berkeley County Sheriff's Department sent a robot into the building to test the air. It found no chemical agents or evidence of an explosion.

Despite the six-hour disruption, postal authorities said the mail would still be delivered Friday.

Postmaster Steve Parrill said about 20 people work in the Ranson branch.