Authorities have confirmed at least 11 people were killed and six injured in a Virginia mass shooting.

The incident reportedly occurred at around 4 p.m. local time Friday at the Public Works building of Virginia Beach’s Municipal Center. Police chief James Cervera told reporters the gunman, who was a current and longtime city employee, was also killed in addition to the 11 victims.

At 4:51 p.m., the Virginia Beach Police Department sent out a tweet advising the public to stay aware from the municipal center. Authorities said they had the shooter in custody at that time, and believed he had acted alone.

Cervera said the suspect was shooting at employees "indiscriminately" inside the building. Officer returned fire and killed the gunman, who has yet to be identified. His motive is currently unclear, but a Virginia government source told CNN the man was a "disgruntled employee."

"This is just a horrific day. And a lot of people are on the scene here," Virginia Gov. Ralph Northam told reporters. "Just our thoughts are for the victims and families. We're working with our law enforcement, first responders, our folks at the hospital and just making sure we take care of everybody right now."

Among those injured was a Virginia Beach police officer, who "was saved by his vest," Cervera said. The identities of the other victims have not been revealed. The conditions of those injured are unknown. 

"We tried to do everything we could to keep everybody safe," Megan Banton, an administrative assistant who works in the center, told TIME. "We were all just terrified. It felt like it wasn’t real, like we were in a dream. You are just terrified because all you can hear is the gunshots."

Multiple agencies, including the FBI, are assisting the investigation. 

Authorities will conduct another news conference at 9:30 p.m. ET. Stay tuned as more information about the case becomes available. 

Since news of the shooting broke, many have taken to social media to express their condolences. Pusha-T, who's from Virginia Beach, was among them.