BLOOMINGTON, Minn. (AP) _ Lubricant on a brake drum and shoe caused an elevator at the Radisson South Hotel to fall 20 stories with 16 people inside, hotel officials said Tuesday.

The 16, who were returning from a dance at about 2 a.m. Saturday, were taken to hospitals, where 13 were treated and released. One remained hospitalized Tuesday in satisfactory condition with back injuries.

Hotel officials had said earlier that the elevator fell and slowed repeatedly, indicating the brakes were working to some extent. On Tuesday, a spokesman for the hotel described the incident as a ''controlled emergency descent.''

Investigators from the Minnesota office of the Occupational Safety and Health Administration determined the cause of the accident. State OSHA Director Ivan Russell said the investigation is continuing to determine how the lubricant got on the brake.

Tom Polski, a spokesman for the hotel's parent company, Carlson Companies, said the hotel contracted with Otis Elevator Co. for maintenance of its three elevators and that they had been serviced the day before the accident.

''This contract states that the elevator company is responsible for all elevator maintenance and inspections in the hotel,'' Polski said.

Calls to the company's Minneapolis office were routed to a night number in Connecticut, where the person answering the phone said he was not authorized to discuss the matter.