The corporate headquarters of Iowa-based Hy-Vee Grocery Stores were locked down for a time Tuesday afternoon. Spokeswoman Chris Friesleben says at first there wasn’t much excitement when an office worker at the corporate campus in West Des Moines came upon an envelope with some white powder in it.

It began about 2 P.M. when the employee opened the letter. Frieslaben says they often get complaints from customers who enclose a sample, so the worker had to think a while before deciding she should turn it in. “We just took all precautionary measures,” Fries says. The West Des Moines fire and HAZMAT crews were called in and workers remained in their offices. She says though they knew what was going on, their day wasn’t disrupted much and there was no panic — just some discomfort because they had to turn off the air conditioning.

The whole thing lasted for several hours and when the specialists determined the substance was not hazardous, employees were allowed to leave. The chain’s website says Hy-Vee has more than 200 retail stores across seven states. The corporate office, on a campus in West Des Moines, includes a 30-thousand-square-foot conference center and a “Hy-Vee History Center,” opened in 1999.