The Hyatt hotel chain was proud of its new facility here, particularly some of the building's more striking architectural features. When the $50 million hotel opened on July 1, 1980, the Hyatt people put out a press release describing it in glowing terms.

"The 733-room Hyatt Regency, Kansas City, the newest building in the city's famous Crown Center complex, opened today," the release began. "Three sky bridges spanning the 60-yard lobby court patterned after the Galleria in Milan and the city's largest ballroom, are highlights of the 40-story hotel."

Today, slightly more than a year later, two of those three sky bridges lie in a twisted mass of steel and concrete rubble on the lobby floor. They came crashing down early Friday night, killing 111 people, most of whom were crushed under the tons of debris that suddenly engulfed a happy scene of dancing couples at the hotel's regular Friday evening "tea dance."

The death toll rose to 113 today, when two people injured in the accident died in Kansas City area hospital.

The hotel remained empty and sealed off from the public today as teams of architectural, engineering and construction experts assembled as part of three investigations -- by the city, the Hyatt corporation and the developers of the Crown Center complex -- into the cause of the tragedy.

The experts, however, had few immediate answers to all the questions surrounding the deadliest disaster in Kansas City's history. What was known was that the sudden and violent chain reaction, which also left 186 people injured, began with the collapse of the highest of the three sky bridges, which spanned the 60-yard hotel lobby at the fourth-floor level.

The steel and concrete walkway was supported by a series of 1 1/2-inch steel rods that extended down from the ceiling of the lobby building, a separate structure adjacent to the main 40-story hotel tower. The rods were attached to steel beams at the walkway base, and it was at those points that the key structural failure apparently occurred.

When the walkway cracked and began to buckle near its center, the massive structure ripped loose from the rods at the base and tumbled down, smashing into another walkway at the second floor level and sending it also slamming into the lobby floor. The walkway at the third-floor level is set off to the side and remains intact.

While it may be weeks before most of the questions are answered, one expert suggested today that the violent chain reaction may have been set off by the same thing that attracted many of the estimated 1,500 people to the hotel lobby at the time of the accident -- the rhythmic sounds of an orchestra playing music from the "big band" era of the 1930s and 1940s.

Victor Papanek, a professor at the University of Kansas School of Architecture, Engineering and Urban Design, said the collapse may have resulted from "harmonic vibration," a phenomenon in which a slight sway in a structure grows out of control, accelerating until the structure itself is destroyed.

Papanek said such a reaction could have been set in motion by the movement of dozens of couples who were dancing and swaying to the sounds of the music on the skywalk just before it collasped.

Papanek, who said he is familiar with the hotel's design and had viewed television videotape of the collapsed rubble, also said the skywalks may have been "underdesigned" for the heavy stress they came under from the large crowds attracted to the Friday evening "tea dances."

He said the steel rods were attached to the walkway base by bolts with "little washers." The used of larger and heavier steel plates to anchor the rods into the base might have prevented the collaspse, Papanek suggested.

Karen Bleche, a representative of Hyatt, said the hotel chain would have no response to this and other suggestions about the cause of the accident. "It is premature for us to comment on what happened," she said.

Bleche said similar "tea dances" were held at a number of Hyatt hotels around the country, but that they are not part of a system-wide activity by the chain.

The free "tea dance" was a popular feature at the Kansas City Hyatt Hotel. The weekly dances were begun in May as a promotion by the hotel management, which reportedly had been disappointed by the initial level of business at the hotel.

Steve Miller, whose orchestra was playing the Duke Ellington composition "Satin Doll" at the time of the collapse, said the dances generally attracted an older crowd but that the big band-era music was also growing in popularity with young people.

Those listed as killed in the accident ranged in age from 11 to 80, but the majority of them were in their 50s and 60s. Many of the victims came from smaller suburbs and towns around Kansas City and as far away as Topeka.

They were people like Neal and Louise OConnor of Kansas City, both in their 60s, both retired. According to a neighbor, Irene Carleton, the OConnors had become regulars at the Hyatt "tea dances."

"They loved to dance," Carleton said of her neighbors, both of whom were killed in the accident.

In the aftermath of the disaster, there was widespread praise here today for the performance of rescue workers, medical teams and others who rushed to help the victims at the hotel Friday night. But while the Kansas City Star boasted that the tragedy had brought out the best in "this decent, civilized city," the accident was also a severe economic setback to a city that has aggressively promoted itself as a major convention center.

The long-range loss may be felt most seriously by one of Kansas City's most prominent families, the Halls, who own Hallmark Cards and control the Crown Center Redevelopment Corp.

Crown Center, begun in 1968 and scheduled for completion in the late 1980s, is planned as a $500 million hotel-shopping-office-apartment complex on 85 acres just south of downtown Kansas City. The Hyatt Regency is one of the two hotels in the complex, which has played a key part in Kansas City's emergence as a national convention center.

A spokesman for Crown Center said today it was too soon to discuss the economic impact. "I don't have any answers to you now," he said.