A building at the University of Minnesota-Duluth was evacuated after a reported chemical explosion around 9:20 a.m. Thursday. Campus officials say a female student who was working in a lab at the time of the explosion suffered minor injuries. UMD officials say nitric acid was involved; it’s unclear what caused the reaction.

UMD Police responded with Duluth, Fire Mayo Ambulance and UMD Environmental Health and Safety. Officials evacuated Voss Kovach Hall and two adjacent buildings as a safety precaution. The scene was later secured, and Duluth Fire Hazmat crews worked to neutralize the chemical and prevent it from spreading.

The incident commander, Fire Chief Shawn Krizaj, explained in a news conference: “We taped the doors shut and worked with UMD engineering staff and mechanical staff to use the HVAC system. We didn’t want it to potentially spread across campus and create a more dangerous situation or area.”

At 4 p.m., the school declared “all is well,” and those who had left belongings were allowed back into the buildings. The UMD SAFE-U alert, sent before 4 p.m., reads: Effective immediately, the building evacuation is canceled and all campus buildings are open and safe to enter.

According to Andrew Kimball of the Office of Environmental Health and Safety, the university is investigating: “We’ll be writing reports. We’ll be involving research safety. We’ll be involving our parent department in the Twin Cities to help us with the investigation. We’ll figure out what caused it and then we’ll figure out ways to prevent it in the future.”

There is no longer any threat to students or society.

Late Thursday morning, UMD sent out an emailed statement regarding the incident:

According to a SAFE-U alert sent at 9:58 a.m., the UMD Police Department, Duluth Fire Department and other authorities responded to the scene of a “chemical explosion that occurred at a laboratory in Voss Kovach Hall.”

UMD wrote in a report Thursday morning that “this was a minor incident with minor injuries and damage.” Campus officials say the building sustained minimal damage and the evacuation was done out of an abundance of caution.