Petrol bombs were thrown at police in Lurgan in the early hours of this morning.
Around 4.30m, police were called after a van was set on fire in the Lake Street area of the town.
It is understood the vehicle was hijacked in the Kilwilkie estate.
When police arrived a short time later, three petrol bombs were thrown in the direction of officers.
The security alert in place has now finished.
Train passengers are being transferred by bus between Portadown and Lurgan. Those using the Enterprise service to Dublin are being taken between Newry and Belfast.
Thousands of Apprentice Boys will march through Lurgan town centre today.
It is expected that around 3,600 participants will be at the parade as well as 61 bands.
— Belfast Telegraph (@BelTel) March 28, 2016