Some loyalist sources are blaming the Ulster Volunteer Force for an early morning bomb attack in east Belfast.
Two houses were damaged in the explosion
Two houses were damaged in the explosion with what police said was a substantial device.
There is a history of feuding involving the Ulster Volunteer Force (UVF) and the smaller Loyalist Volunteer Force (LVF).
The LVF emerged out of the UVF in 1996 after a row involving one of its leaders, Billy Wright, who was "stood down". There have been many exchanges of gunfire and past killings between the two groups.
Police were alerted to the blast shortly after 0100 BST on Saturday.
When they arrived at the scene at Bloomfield Court, just off the Beersbridge Road, they discovered two houses had been extensively damaged.
The windows in both houses were shattered and the doors were hanging off their hinges.
The police said the device was placed on the doorstep of a house.
It was empty at the time of the explosion.
It is believed that house was the intended target of the bomb.
A man who did not want to be identified said a package had been left at his front door.
He said it was fortunate that he and his son were not there at the time.
"It was definitely an attempt at murder," he said.
"Since they didn't take into consideration the people next door to me they have attempted to murder them as well.
"By the grace of God, nobody was killed."
A PSNI spokesman said: "It wasn't a big bomb, but we are describing it as an important device."
Sam Cowan and his wife were asleep next door when the bomb went off.
Mr Cowan, 70, was treated at the scene for shock. He has a heart condition.
He said: "I came down with my wife because one of our neighbours had come over and knocked and got us out of bed.
Sam Cowan surveys the bomb damage to his house
"He brought us round to his house and I had to hold onto his shoulder - he called an ambulance and I had already collapsed, almost in his living room."
The police have not yet confirmed what sort of device caused the explosion.
The UVF was behind the murder of Brian Stewart in east Belfast on Tuesday.
The killing has been linked to feuding with the Loyalist Volunteer Force.
East Belfast Ulster Unionist assembly member Michael Copeland condemned the bomb attack.
He said the damage inflicted on innocent families was beyond justification.