A home-made bomb has gone off in the North Shore suburb of Forrest Hill this afternoon, and police are searching for the source.
The explosion was in a small stand of bush at the south end of Greville Reserve, near a Watercare pumping station, and three fire appliances were called to the reserve around 2pm after the explosion was heard.
Raj Patel, the manager of the Good2Go convenience store directly across the road from the reserve, says he called the police after hearing a "huge bang".
"Loud is not the word. I'm 49 years old - I've heard car crashes, explosions on TV - nothing as loud as this," he says.
"The smoke was rising taller than the trees."
Mr Patel says there was a strong ammonia smell following the explosion.
"The kids came running in saying 'The ammonia is in my eyes'."
A police canine unit was also called to the scene.
Police left the scene holding at least four brown paper bags but would not answer questions as to what was inside.
A fire service spokesman confirmed an "improvised explosive device" had been detonated in a patch of bush near a group of six WaterCare sheds.
St John paramedic Phil Marlow says there are no injuries to report at this stage.
"There was just a big bang and here we are."
Fire and police responded as it was initially thought to be a larger explosion than it turned out to be.
The communications spokesman said it appeared to be "something that someone's put together inside a cannister".
Anyone who saw any suspicious activity in that section of bush was asked to call police.