LONDON (Reuters) - Five prison officers were assaulted at a maximum security jail in England on Thursday and British counter-terrorism police opened an investigation, a police spokesman said.

London Police said officers from its Counter Terrorism Command were leading the inquiry into the incident at Whitemoor prison in central England.

The BBC reported that two inmates, one who was serving a sentence for terrorism offences, had carried out the attack using bladed weapons and were wearing fake suicide vests.

“Due to certain circumstances relating to this incident, it was deemed appropriate for the investigation to be carried out by officers from the Met Police Counter Terrorism Command,” a police spokesman said.

“However, we must stress that at this early stage of the investigation we are keeping an open mind with regards to any motives and enquiries to establish the full circumstances of the incident are ongoing,” the spokesman said.

In 2016, Britain announced plans to isolate radical Islamists in special units in high security jails to limit their ability to influence other inmates amid concerns that prisons were breeding grounds for extremists.