A worker in Portsmouth, Massachusetts was seriously injured after he and the excavator he was operating, to demolish the Olde Port Traders building, fell through an "unsupported" basement ceiling, eight to 10 feet below, said Fire Chief Steve Achilles.

Achilles said the worker was demolishing the rear portion of the 28,000-square-foot building, when he drove over an "extended basement" and he and the heavy equipment fell through the asphalt.

There was no visible hole in the ground prior to the accident, Achilles said.

The worker was initially transported by local ambulance to Portsmouth Regional Hospital and because his injuries were thought to be serious, an extra firefighter attended to him during the ambulance ride, Achilles said. From the Portsmouth hospital, the worker was later transported to a Boston hospital with fractured vertebrae in his back, Achilles said.

SCollins said another worker placed a ladder into the ground where the excavator fell and the injured man climbed out.

The city building inspector and federal Occupational Health and Safety Administration were notified, said the fire chief. OSHA was called because of the "potential for serious injury," Achilles said.

Work was temporarily stopped until an OSHA representative investigated and authorized the demolition to resume, according to the fire chief.

M. Bradsher Co., Inc. is the demolition contractor.