The eight people arrested by terror police in Birmingham were allegedly planning an Iraq-style kidnap and execution, Sky News has learned. Sky's Crime Correspondent Martin Brunt says the plot involved randomly snatching an individual off the streets.
The kidnappers then intended to release a video of the hostage pleading for their life and make various demands.
The suspects were detained under the Terrorism Act after a six-month surveillance operation involving officers from two forces.
More details will be given at a police briefing at 11.30am, followed by a press conference at 3pm.
Brunt said officers feared the alleged plot was "coming to fruition".
The fact it "would not have resulted in a mass casualties" suggested a "chilling new departure" in terror tactics.
The suspects had been tracked in a combined police operation led by the Midlands Counter Terrorism Unit.
They were supported by officers from the West Midlands police and the Metropolitan Police.
Officers swooped on a number of addresses in the Sparkhill and Alum Rock areas of east Birmingham at 4am.
West Midlands police said the eight were held "on suspicion of the commission, preparation or instigation of acts of terrorism under the Terrorism Act 2000".
Their statement added: "A number of addresses in Birmingham have been secured and sealed off and are currently being searched.
"Whilst this operation poses no specific threat to the West Midlands, as a precautionary measure we will have an enhanced police presence at these locations.
"Our message to people living in the West Midlands is to remain vigilant. Public safety is our absolute priority."
A Home Office spokesman said: "This operation is a reminder of the real and serious nature of the terrorist threat we face."
Today's arrests come after police detained a total of five people in anti-terror raids in Manchester and Halifax, West Yorkshire, last week.
As I told Paul Burgin, if I were ever abducted by terrorists, "I would never give them the satisfaction of spouting their propaganda on a videotape.... in exchange for my life. They are going to kill me anyway, so I would rather die for what I believe in as a martyr for Christ and liberty."