UPDATE, 3:27 p.m. National Grid arrived and shut off the gas.
Firefighters and police are on Amory Street between Boylston and School streets for a natural-gas leak inside 192 Amory St. that started around 2:50 p.m.
Police have blocked Amory and are evacuating neighboring buildings as they await somebody from National Grid to try to shut the gas off. At least 14 neighboring residents are now being sheltered on Marbury Terrace.
Police had to ask pilots of news helicopters to back off because of the risk the building could explode.