MADISON, Wis. — A pier collapsed at Memorial Union Terrace on Labor Day, injuring around 20 to 25 people, University of Wisconsin-Madison police confirmed.

Police said the collapse happened at around 2:35 p.m. Monday. They estimate around 60 to 80 people were on the pier when it collapsed.

UWPD, Madison Fire Department, the Dane County Sheriff’s Office, Wisconsin Union staff and Dean of Students Christina Olstad all responded, providing aid and assistance.

Police said they do not know how many people the pier can hold.

“There were way too many kids on the piers. They were packed. There was no warning. All of a sudden it went down and people were in the water," said Debra Drewek, a retired nurse who was taking pictures at the terrace when the collapse occurred.

She said many of the people on the collapsed section swam to shore and that others clung to the pier and waited for rescue boats to arrive. Drewek said most of the injuries appeared to be leg scrapes, and that “a lot of kids were crying because they had laptops, wallets and phones underwater.”

(Photo Courtesy of Ryan Piaskowy)

In the collapse, about two dozen people were hurt, but none were severely injured. Police said at least one person was transported for treatment of non-life-threatening injuries. Five others were treated by EMTs and paramedics and were released on the scene.

There were no lifeguards on the scene when the incident occured, according to police.

A video circulated on social media Monday night showed the moment the pier collapsed.

Police said the Madison Fire Department’s dive team has cleared the area around the pier. University PD said they were providing an email for people on the pier who may have lost property.

Following the incident, the pier will remain closed. It was scheduled to be removed on Tuesday for the end of the summer season.

Police said UW-Madison will investigate the incident

The Associated Press contributed to this report. This story is developing. Check back for updates.