Traffic was brought to a standstill in Belfast tonight as police investigated an abandoned vehicle under a motorway bridge.
Commuters faced a nightmare journey home after the M2, M3 and the northbound carriageway of the Westlink through the city were all closed for a period.
A series of roads around the vehicle near the city docks - including York Road, Dock Street, Brougham Street and Garmoyle Street - were also sealed off.
Cars were bumper to bumper in a grid-locked city centre as motorists sought alternative routes.
Many of the roads were later re-opened.
The incident was one of a series of security alerts throughout the city during the day. Most transpired to be hoaxes but a viable explosive device was discovered near the university area last night.
A number of homes were evacuated after the pipe bomb was discovered in an alleyway off Eblana Street near Queen’s University.
A controlled explosion was carried out on the device during the alert.
A hoax also caused widespread disruption in Derry today.
Last night, four men and a woman were arrested in connection with dissident republican terror activities.
The men - aged 28 to 44 - were taken into custody in the greater Belfast area.
A 29-year-old woman was detained later, police said.
The suspects are being questioned by detectives from the police’s serious crime squad in Antrim.
Police asked the public to be vigilant following the security alerts.
A PSNI spokesman said: “There is an increased police presence as police deal with this series of alerts.
“Some are hoaxes but at least one so far has been a viable device. We need to treat each incident with an appropriate level of caution, for everyone’s safety.
“Disruption will be kept to a minimum but safety is paramount. We would ask everyone to be vigilant - at home, at work and while travelling.”
PA