She did not immediately provide details.
Minutes before, Gloucester County prosecutor Charles Fiore said at a news conference that police were in speaking via telephone with a man holding two women hostage at the facility.
The women had not been harmed, he said, but details of the hostage situation were not clear as the three were barricaded in a room at the facility. The women are UPS employees, he said.
Though shots were fired, there are no reports of injuries, Fiore said at the time.
Thirty-two UPS employees were evacuated to a Holiday Inn, about 10 minutes away, Gloucester County spokeswoman Debra Sellitto said.
Police have restricted travel on two roads near the facility, she told CNN. The incident is confined to the UPS building, Sellitto said.
The county received word of an active shooter situation around 8:30 a.m. ET, she said.
The building, located in an industrial district of the south New Jersey township of 6,000, is a bulk mail processing facility, UPS said.
“We are working with law enforcement as they respond and cannot provide information about the identity of people involved at this time,” the company said on Twitter.
In a tweet just before 10 a.m. ET, the New Jersey State Police said local police were responding to an incident in Logan Township.
The township’s school district is under modified lockdown, and no one can enter or leave any of its schools after police notified the district of “police activity in a nearby industrial park,” Superintendent Patricia Haney said.
The nearby Swedesboro-Woolwich School District said it is monitoring the situation. The students are safe, the district said in a note to parents.
CNN’s Chris Isidore, Julia Jones, Evan Simko-Bednarski, Kristina Sgueglia and Aaron Cooper contributed to this report.