A support frame collapsed at a high-rise construction project Saturday, killing three workers who became trapped in quick-drying concrete as co-workers dug to try to free them, authorities said.

The workers were on the 27th level of the building, pouring its concrete roof, when the supporting frame structure below them gave way, dropping them to the 26th floor, said Capt. Al Cruz of Miami-Dade Fire Rescue.

A 3-foot layer of hardening concrete completely encased one worker and partially buried the others, fire rescue officials said. The cause of the frame collapse was not immediately determined.

The identities of the three workers killed were not immediately known. A fourth worker was taken to a hospital with suspected heart trouble, authorities said.

Police identified the building project as One Bal Harbour. It is to be a 26-story condominium with an adjoining hotel, according to the Web site for Bonita Springs-based

A message left for the construction company was not immediately returned.

"Today's event was very unfortunate and our thoughts are with the families of those who were involved," the company said in a statement released to The Miami Herald. "We take great care to ensure the safety of construction crews, but at this time we have no information about what may have occurred."

The building had passed all inspections, said Dan Nieda of Bal Harbour's building department.

Bal Harbour, just north of Miami Beach, is known for its tall hotels and high-end shopping.