An investigation is underway at Viracon in Owatonna, Minn., after a bomb threat was reported at its facility early Saturday morning.

According to police, the Owatonna Police Department (OPD) responded to a complaint at around 3:30 a.m. after officers were advised of a written bomb threat on a wall inside the facility.

During a sweep of the business, a suspicious package was discovered by staff, and the area was secured until the St. Paul Police Department bomb squad arrived. The package was determined to be construction materials, according to police, and officers cleared the scene shortly after 8:30 a.m.

“The incident remains under investigation with Viracon staff and to protect the integrity of our investigation, we are not making any further statements,” OPD Captain-Detective Bureau Commander Jeffrey E. Mundale said in response to™’s request for comment.

Annette Panning of Viracon says the company cannot provided any detailed information with the investigation ongoing.

“I can tell you that Viracon takes this type of threat seriously,” she says. “Even though it proved false, it is disturbing to our employees and to the broader community. It will be fully investigated and Viracon will exercise all means at our disposal to identify the individual and to process charges.”

St. Paul police hadn’t responded to a request for comment as of press time.

This is the second Viracon-related incident making news this month. Last week, a truck driver was critically injured and later died after thousands of pounds of glass fell onto him as he unloaded a delivery at Viracon’s St. George, Utah, facility.