CARRABASSETT VALLEY – At least five people were injured Saturday night when a fire escape at the Rack bar and grill collapsed beneath partygoers.

The wooden fire escape collapsed about midnight and sent at least 10 people tumbling 15 feet to the ground below, with the small platform and staircase crashing onto rocks and uneven ground, police said.

Two men and two women hurt in the collapse were taken by ambulance to Franklin Memorial Hospital in Farmington, with injuries ranging from broken bones to cuts and bruises, said Carrabassett Valley Police Chief Scott Nichols.

A fifth person was taken to the hospital in a personal vehicle, said Sgt. Ken Grimes of the state Fire Marshal’s Office, who is investigating the collapse.

Peggy Cannon, a clinical coordinator at the hospital, said Sunday that three of the five people were treated and released. Of the remaining two, one patient was admitted Sunday and the other was transferred to Central Maine Medical Center in Lewiston, she said.

Nichols would not release the victims’ names Sunday, but he said three of the four transported by ambulance were Maine residents with ages from 26 to 51.

He said the partygoers should not have been on the second-story fire escape, which was “well marked” as an emergency exit with a “big red sticker” on the door.

“I think it was just too much weight,” Nichols said.

He said it will take a couple of days to determine an official cause and complete the incident report.

Jeff Strunk, co-owner of the Rack, declined to comment on the incident. He said he owns the bar and grill with snowboarder Seth Wescott, the 2006 and 2010 Olympic gold medal-winner, and Chase McKendry.

Nichols said the bar and grill had a near-capacity crowd, with people coming from the Reggae Festival held earlier Saturday at Sugarloaf ski resort. He could not give the number of people at the Rack when the collapse occurred.

No bar staff was on the second floor at the time of the collapse, Nichols said in a phone interview. Witnesses said a “few” people got onto the fire escape platform and the entire structure collapsed when at least 10 people piled onto it, he said.

Citing accounts of the collapse, Nichols said, “People were on top of each other; it was just a mess.”

The Fire Marshal’s Office is investigating the collapse because there were injuries tied to a fire escape system, according to Grimes, who said other law enforcement agencies will determine a cause.

Grimes could not give the age of the fire escape, but said that “looking at the materials, it looks fairly new.”

“I didn’t detect any rotting in the wood,” Grimes said in a phone interview.

“The balcony gave way, presumably, under the weight,” he said.

It’s unclear if an alarm system attached to the fire escape door went off, Grimes said. “I’m not aware if it was working or if it went off,” he said.

Grimes could not say if the law required the fire escape door to have an alarm system.

Grimes also could not say Sunday if the fire escape had any code violations or certification issues.

The restaurant was cleared Sunday to reopen the first floor only. The upstairs is closed until the fire escape can be repaired, Grimes said.

The Rack is located on the access road to Sugarloaf, but it is completely independent of the ski resort, according to Sugarloaf spokesman Ethan Austin.