Fire consumed a law office on Duckworth Street in downtown St. John's on Saturday morning. (John Gushue/CBC)

A large fire destroyed a prominent law office in downtown St. John's Saturday, pushing smoke over much of the Newfoundland and Labrador capital.

Premier Danny Williams said he was relieved no one was hurt in the fire that destroyed a building where he worked for almost two decades. (CBC)

St. John's Regional Fire Department crews fought flame and smoke that had engulfed the Duckworth Street offices of Roebothan McKay Marshall, which was co-founded nearly 25 years ago by Premier Danny Williams. The building is adjacent to the National War Memorial near the harbour in St. John's.

By lunchtime, part of the building caved in. An excavator was called late in the afternoon to begin demolishing the fire, which took hours to extinguish. The structure of an adjacent building used by the firm remained standing, but it's not clear how much damage it sustained.

All of the firm's 65 employees were accounted for and no injuries were reported, said Steve Marshall, a partner in the firm. Marshall said computer servers holding the firm's data are intact.

Williams was one of a group of spectators that saw the building begin to collapse from fire and water damage.

Firefighters spent hours extinguishing a blaze at Roebothan McKay Marshall's office building in downtown St. John's. (John Gushue/ CBC)

"I spent a lot of time in that building working with a lot of wonderful people," Williams told CBC News.

"It's a sad moment. It's a nostalgic moment, when you look at a building going up in smoke. But on the other hand, the practice there is not about the building, it's about the people," he said.

"The beauty is that no one was hurt. A building is just a building."

Williams started the firm, which has had specialties in litigation, labour law and personal injury claims, with Jack Harris, who currently serves as the NDP member in the House of Commons for St. John's East.

In an interview, Marshall said while he is relieved that at least digital records of the firm's work are safe, his main concern has been staff and personal security. No one was in the building when the fire broke out.

Lawyer Steve Marshall: 'As long as no one's injured … that's the blessing there. The rest of it? We'll get through this.' (CBC)

"We have a very large law practice. We generate an enormous amount of paper, but we can recreate that," he said in an interview.

"As long as no one's injured … that's the blessing there. The rest of it? We'll get through this."

Nearby buildings were not damaged by the fire.

Eyewitnesses reported seeing smoke seep out of the roof of the three-storey building around 7 a.m. Within an hour, the fire had generated thick, dark smoke that was visible for miles in St. John's. Its bitter smell was noticeable in neighbourhoods across the city.

Fire crews punched out windows to let smoke and heat out of the building. Flames and sparks could be seen darting from third-storey windows even after the building had been doused with water.

Fires are often a stubborn problem in downtown St. John's, where many buildings have layers between walls that can confound crews.

The Royal Newfoundland Constabulary closed down a section of Duckworth Street to help crews fight the fire.