(Releads with authorities reopening city center)
OTTAWA, May 2 (Reuters) - Police in Canadian capital Ottawa on Tuesday temporarily shut down four city center blocks, including a building where the prime minister works, after a mechanical digger ruptured a natural gas pipeline.
City authorities said in a tweet at 6 pm eastern (2200 GMT) that the area had been reopened. The leak started at around 1:30 p.m. eastern.
The evacuated buildings included the Langevin Block on Wellington Street, where Prime Minister Justin Trudeau and his senior staff have offices. He also works out of the Parliament building across the street, which stayed open.
Kathryn Keyes, a spokeswoman for the consortium overseeing the construction, said the operator of the excavator hit the gas pipeline during landscaping work on one of the streets above the light rail line.
Crews have been digging up city center streets for several months as they build a new underground light rail system. The project has been disrupted by several mishaps, including a sinkhole.
The smell of natural gas filled the air downtown. Workers from nearby buildings were moved to the front lawn of Parliament Hill while several buses lines were rerouted, causing severe transit delays. (Reporting by David Ljunggren, Andrea Hopkins and Leah Schnurr in Ottawa and Anna Mehler Paperny in Toronto; Editing by Jeffrey Benkoe and Grant McCool)