Police have been carrying out searches in Craigavon
Two guns have been recovered close to where a policeman was shot dead in Northern Ireland last week.
Constable Stephen Carroll, 48, was shot dead by the Continuity IRA in Craigavon last Monday. A total of seven people are being questioned about the murder.
A gang of about 30 youths threw bottles and stones at police in Craigavon on Monday evening. A van was hijacked and set alight in the Tullygally area.
It is understood searches have been continuing after the discovery of guns.
In nearby Lurgan, the annual St Patrick's Day parade has been cancelled due to tensions in the area.
The decision was taken on Monday night at a meeting of St Peter's GAA club, which organises the event.
In a statement, the club said the "scenes of violence and destruction in Lurgan and Craigavon within the last seven days have created considerable anxiety and concern within the local community".
At the weekend, police in Lurgan came under petrol bomb attack from rioters as they carried out searches in connection with the investigation into the Real IRA murder of two soldiers in Antrim on 7 March.
Youths threw missiles and petrol bombs as police carried out searches
Soldiers Mark Quinsey, 23, from Birmingham, and Patrick Azimkar, 21, from London, were shot dead by the Real IRA at Masserene Army barracks.
Police have been given until the weekend to continue questioning four men aged 41, 32, 31 and 21 in connection with the killings.
The murders of the two soldiers and a policeman in the space of three days sparked widespread outrage across Northern Ireland.
Detectives investigating the murder of Constable Carroll, who was shot while on duty in Craigavon on 9 March, arrested two more people on Monday, while police were given an extra five days to question a 21-year-old man.
A total of seven people are being questioned in connection with the attack.
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