Three police officers, a paramedic, a gas engineer and an elderly man have been seriously injured in a gas explosion in Gateshead.
Police were called to a bungalow on Marian Court at 17:30 BST on Monday.
While officers were inside the property there appeared to have been an explosion, police said.
All six men were taken to Newcastle's Royal Victoria Infirmary. Their injuries are not thought to be life-threatening.
The police officers are believed to have severe burn injuries.
Officers were met with a strong smell of gas when they arrived after concerns were raised for the safety of the elderly man in the bungalow.
Northumbria Police Det Supt Dave Byrne said: "It has been a sizeable force that has caused the damage."
"On arrival, [the officers] could smell the gas and they knew the man inside was an elderly gentleman.
"The concern was for his well-being in light of the fact he's inside the house and there was a strong smell of gas."
He could not be sure yet where the officers were when the explosion happened.
The injured paramedic is a member of the hazardous area response team who is trained to deal with non-standard 999 calls.
"It's never nice when one of our own is injured and we are obviously thinking about him," an ambulance service spokesman said.
Sean McKee, from Tyne and Wear Fire and Rescue service, said: "There were police officers trying to remove the elderly gentleman from the property when the blast happened.
"They removed the gentleman but sustained various injuries which has resulted in them being taken to hospital.
"The officers tried to vent the property while trying to remove the gentleman from the property."
One eyewitness told the BBC: "It was a huge explosion which shook neighbouring properties and destroyed the bungalow."
A spokesperson for the Northern Gas Networks said: "Our engineers isolated the gas supply to the properties affected by the gas explosion in Gateshead and have made the area safe.
"We can confirm that the explosion was not the result of any issue with the local gas network."
Neighbouring flats have been evacuated.
A full investigation into the cause of the explosion is due to begin on Tuesday.
The Health and Safety Executive has been informed and will take the lead in the investigation.