Four men are being questioned on suspicion of committing terror offences after a police raid in West Yorkshire.
Metropolitan Police anti-terror officers arrested the men following the operation at University of Bradford halls of residence on Friday.
A police spokeswoman said three of the men - two aged 18 and one aged 19 - are being held in London. The fourth, aged 19, is being held in West Yorkshire.
The arrests were not in connection with last July's London bombings, she said.
West Yorkshire Police assisted in the raid, which took place at 2300 GMT.
The Scotland Yard spokeswoman said the four were arrested on suspicion of the commission, preparation or instigation of acts of terrorism under the Terrorism Act 2000.
A university spokesman said they were all thought to be students, but did not disclose their nationalities.