A mechanical failure caused an explosion Friday at the University of Nevada, Reno, injuring eight people and causing the partial collapse of a mostly empty dormitory building, authorities said.

Photos posted to social media showed extensive damage spanning multiple floors of Argenta Hall. Windows were blown out and debris appeared to have fallen on the street below.

Student Raven Green said she was in her room watching Netflix when she heard a loud boom and felt the building shake.

She thought it was an earthquake. When she opened her door, she could hardly see in the hallway that was full of smoke and debris, with water spraying everywhere.

“It was very scary,” she said.

Two people were taken to a hospital and quickly released and six others were treated for injuries at the scene, Reno fire operations chief Steve Leighton said.

Police and fire crews were searching the building but did not believe anyone else was inside.

“We are … lucky that today with a light day coming after a holiday that we really didn’t have anybody in those halls,” said Todd Renwick, the university police chief.

Officials had not determined the specific cause of the explosion but said it was the result of some kind of mechanical failure in the basement of the seven-story building.

Firefighters arrived at the building after a small blast and were there when a bigger explosion damaged Argenta Hall, Leighton said. The explosion also damaged Nye Hall which is attached to Argenta Hall.

Leighton said authorities haven’t been able to thoroughly search the basement, which is flooded with about two feet of water.

Green, 19, said she had climbed over doors and pieces of drywall but found the stairs broken. She raced back to her room to get out of the smoke and called 911 for help. She was later evacuated.

Sophomore Raymond Floyd was in his room across the street in Peavine Hall studying for a calculus final when he heard a loud noise. At first he dismissed it as someone slamming a door. Then the fire alarm went off.

About 10 minutes after his building was evacuated, there was a “much bigger and louder” explosion, he said.

“I could see smoke and shrapnel in the air and parts of the roof flying off,” Floyd said.

He headed to Argenta Hall, where he said it appeared the explosion had torn through laundry rooms on each floor.