The men were detained in Luton outside London
Four men have been arrested in Luton on suspicion of committing terrorism offences, police in the UK have announced.
According to a statement from the Metropolitan Police, the men were believed to be involved in the "commission, preparation and instigation of acts of terrorism".
"Searches are being conducted at seven separate addresses in Luton in connection with this investigation," police said.
"A number of vehicles are also being searched."
Police say the arrests are not connected to last month's Paris terrorist attacks.
Officers from the Met's Counter Terrorism Command and the Eastern Counter Terrorism and Intelligence Unit were involved in the raids.
The four men - all aged in their 30s - remain in custody in a London police station.
The government has previously said that seven plots to attack targets in Britain have been thwarted by security services in the past year.