St. Croix County authorities said a potentially dangerous situation was discovered at a Somerset apartment where a man was later arrested.

Sheriff Scott Knudson said “suspected bomb material” was found Friday morning in a unit at the EZ Living Apartments complex on Main Street.

A 30-year-old resident was arrested and was being detained in St. Croix County jail on a Department of Corrections hold, Knudson said. Formal charges, he said, could be filed as soon as Monday.

The St. Paul bomb squad was first called to the scene, the sheriff said. All the suspicious materials were removed and taken off-site, where Knudson said they were being investigated. The Marathon County bomb squad and a hazardous materials unit from Eau Claire were also called to assist, according to the sheriff.

Knudson didn’t describe the materials, but said they “have given us cause for concern.”

The discovery occurred at about 3:30 a.m. Friday, March 9, by a deputy who was making a death notification at the unit. Knudson said the deputy spotted suspicious items while performing the duty and began an investigation that led to multiple squad cars descending on the apartment grounds.

He gave full credit to the deputy, Charles Coleman, for preventing a potentially dangerous outcome.

“He may averted a future tragedy for whatever destination” the materials were bound for, Knudson said, adding that he’s “relieved and satisfied” with the outcome.

The incident prompted authorities to temporarily evacuate some neighbors during the investigation.

Two neighbors living near the unit said the incident was alarming. Both neighbors said the man arrested was “polite” and didn’t cause trouble at the complex.

Knudson said the FBI was contacted and is involved in the investigation.