text: Five people died and dozens were hurt after an attacker - now named as Khalid Masood - drove a car on a pavement, stabbed a policeman and was shot dead by police in the grounds of Parliament.
  Addresses in Birmingham and London have also been searched.
  Dyfed-Powys Police said the search in Carmarthenshire concluded on Thursday.
  A force spokeswoman said: "The Wales Extremism and Counter Terrorism Unit, supported by officers of Dyfed-Powys Police, have today provided assistance to The Metropolitan Police, following yesterday's incident in London.
  "In doing this, they have conducted a search of one property in Carmarthenshire - this search has concluded.
  "The occupants are receiving appropriate support. They are not suspects and have not been arrested."
  There is no threat to the area, the force added, having earlier said it was "increasing patrols".
  On Thursday evening, the Met confirmed a 75-year-old man was the fifth person to die in the wake of the attack.
  The force said eight arrests have been made in the capital and in Birmingham - three women and five men - with searches at addresses in Brighton and south east London having now concluded.
  Earlier, police formally identified the man believed to have been responsible for the Westminster attack as Masood, a 52-year-old from Kent who was born Adrian Elms and who was thought to have most recently been living in the West Midlands.
  Police said Masood was not the subject of any existing investigations and there was "no prior intelligence about his intent to mount a terrorist attack".
  However, he was known to police and had a range of previous convictions for assaults, including causing grievous bodily harm, possession of offensive weapons and public order offences.
  South Wales Police and Gwent Police said they were reviewing their respective security arrangements in light of the incident and there would be an increase in police presence in busy areas.
  North Wales Police has asked people to remain vigilant and report anything suspicious.
  The Islamic State group has said it was behind the attack.
  Those killed by the attacker include PC Keith Palmer, Aysha Frade, who worked at a London college, and Kurt Cochran, 54, from Utah, United States.
  Seven of the injured are still in hospital, with five in a critical condition and two having life-threatening injuries. A further 29 were treated in hospital, police said.
target: Detectives investigating Wednesday's terror attack in London have finished searching an address in Carmarthenshire.