A man is fighting for life in hospital and three police officers have been injured following a townhouse explosion during an armed stand-off with bailiffs.
The blast took place just before 11.50am, following claims residents were being threatened by a man armed with an axe and knife in Finsbury Park.
Bailiffs and emergency services turned up at the home, with an explosion taking place inside shortly after police arrived.
Seventy-two fire fighters tackled the resulting blaze, which saw the entire Stapleton Hall Road property's basement go up in flames.
The Met Police said the armed man inside the property, aged in his mid-50s, was taken to hospital with serious burns.
He is said to be in a life-threatening condition.
Three officers - a man and two women - were also hurt in the blast.
They are currently in hospital but their injuries are not thought to be serious. Police said one of the officers suffered an injry to their arm.
A witness told the Standard: "When the bailiffs came the man chased them around with an axe and knife.
"The police were called and came to try and calm him down.
"He ran into the basement and the police were trying to talk him round. That's when the explosion happened. I think it was with gas."
Lauren Packham, 21, said she was half asleep in a neighbouring house when she heard shouting.
Miss Packham, of Cambridge, who was visiting a friend, said: "I got up and looked out the window and I saw a man in his fifties running up and down with a large kitchen knife, about six inches long.
"He seemed to be chasing someone. I went to sit back down and I heard what sounded like fireworks. The man went to run back inside."
She said she could smell smoke and then looked out and saw "a big fire going up".
The London Air Ambulance was scrambled to the scene and the property was evacuated. One person had managed to get out the house before the Fire Brigade arrived.
No neighbouring properties are thought to have been affected by the blaze.
A Scotland Yard spokesman said on Wednesday afternoon: "Enquiries into the cause of the explosion are ongoing.
"This incident is not being treated as terrorism related."
"The address has been evacuated as a precaution but no neighbouring properties are affected," he said.
"Emergency services are working together to make the scene safe and to begin a thorough investigation into the circumstances."
A spokesman for the London Fire Brigade said the blaze was under control by 3.30pm.
The incident has also been referred to the Met's Directorate of Professional Standards and the IPCC as a matter of course.
Haringey Borough Commander Chief Superintendent Helen Millichap said: “This is a serious incident where several of my officers have been injured as well as a man at the property who remains in a critical condition.
"We are still investigating what happened and exactly how the explosion occurred. The officers who responded to this call faced a dangerous situation and I am proud of the courage they showed.”