DULUTH — A large portion of the Miller Hill Mall's roof collapsed Tuesday morning, spilling a hill of snow, structural supports, wires and ceiling tiles onto a concourse between Express and a Caribou Coffee kiosk at the 50-year-old shopping center.

No injuries were reported, according to city spokeswoman Kelli Latuska.

Shops were not yet open when emergency authorities were called at 9 a.m., but mall walkers and staff were on-site. The building was evacuated and is closed, including Essentia Health's Miller Hill Health Plaza and the St. Louis County Auditor Service Center, both located in different areas of the 800,000-square-foot mall.

Barnes & Noble manager Scott Skar said he heard a loud noise, "like something rolling across the roof."

He saw snow in the concourse that reached the ceiling — and a gaping hole.

"It was shocking to see open sky," Skar said.

Before the collapse, a crew was on the roof clearing off the most recent snowfall. They had cordoned off the concourse beneath them while they worked, according to Duluth Fire Chief Shawn Krizaj. The workers reportedly stopped and evacuated when they heard "popping sounds."

The Duluth branch of the National Weather Service, which is about 4 miles from the mall, said it had received 12.5 inches of snow during the most recent storm system.

The Duluth Fire Department conducted several searches to make sure no one was buried in the snow and debris. All mall employees and mall walkers had been accounted for, Krizaj said.

The Miller Hill Mall has more than 100 stores and is owned by Simon Property Group, which said in a statement that it would update its website with information about when the mall would reopen.

"We are grateful there were no injuries as a result of a portion of the roof collapsing and for the swift response of first responders," the statement said.

There was an initial gas leak, but by midmorning the building's gas, water and power had been turned off and structural engineers were assessing damage. Yellow caution tape was strung in front of mall entrances and shoppers were turned away before they reached the doors.

The Fire Department is asking people to stay away from the mall and keep drones away, too.