Police officers lured towards a bomb were lucky to escape with their lives when the device exploded close to them.
Three officers on patrol were responding to a call-out in north Belfast when the blast occurred. The PSNI is treating it as a murder bid.
A spokeswoman said: "Police can confirm that an explosive device detonated. It is believed that the target was police officers and police are now treating it as attempted murder."
The officers were not injured but left badly shaken, she added.
Officers were responding to a call out in the Hazelbank area and were making their way along Duncrue towpath near the M5.
After the explosion at around 9.15pm, the M5 was closed and the area sealed off for 24 hours.
Chief Superintendent Henry Irvine said: "This is a well known area that is used every day by members of the local community.
"It is only by good fortune that police officers and members of the public were not killed or seriously injured last night.
"Those who carried out this attack have shown complete disregard for the safety of the local community and the police officers serving this community."
The M5 re-opened on Sunday night, although the towpath is closed.
It followed loyalist violence on Friday night, when a mob of up to 100 attacked police with missiles in Glengormley.
The constituency office of Justice Minister David Ford was also damaged.
It is understood the disorder erupted after loyalists tried to remove Irish Tricolour flags from lamp posts and were challenged by police. A loyalist flag protest was held in the area two hours earlier.
The serious violence has prompted questions about the decision of the First and Deputy First Ministers to leave Northern Ireland on a business promotion trip to Brazil.
Peter Robinson and Martin McGuinness jetted off to Brazil on Saturday, hours after the loyalist riot injured five PSNI officers.
On Sunday, as a picture of a smiling Mr Robinson and Mr McGuinness in Brazil was released, Alliance MLA Stewart Dickson accused them of double standards.
He said: "I do not have a difficulty with them being abroad trying to sell Northern Ireland but I am disappointed that united front was not demonstrated here from Christmas until now.
"How can they demonstrate that united face abroad and not at home? There's a fair dose of irony in that situation. Since the issue arose in December there has been no active demonstration by both of them together to call an end to the protests.
"I would hope that any benefit of them travelling together and sharing time together will help them develop a wider view of the world and that by the time they do return they will bring a sense of calm and leadership for Northern Ireland that has been lacking for quite some time."
TUV boss Jim Allister also hit out at the trip which will see the first ministers visit California and Washington as well.
Mr Allister wrote on Twitter: "As taxpayers fly Peter and Marty and entourage to Brazil for a week is it perception or reality that 30C in Sao Paulo beats 30F in Belfast?"
The ministers have travelled to Brazil in a bid to forge new links with what is one of the world's fastest-growing economies.
They will be visiting Sao Paulo, Brasilia and Rio de Janeiro. They hope to promote economic development, trade, tourism, university and sporting links between Brazil and Northern Ireland.
Mr Robinson said: "Our Programme for Government placed our economy as the key priority. We will leave no stone unturned as we continue to identify new markets and promote Northern Ireland in Brazil.
Mr McGuinness said: "The only way to develop international relationships is through face to face meetings.
"Our presence here demonstrates to the Brazilians that we are committed to exploring mutually beneficial opportunities to grow our economy."
Five facts about Brazil
- It has the biggest rain forest in the world, the Amazon
- Brazil has won the soccer World Cup five times
- Brazil has one of the New Seven Wonders of the World, the Christ the Redeemer statue in Rio de Janeiro
- Brazil’s official language is Portuguese but there are more than 180 native languages spoken in the country
- Brazil is the largest Catholic nation in the world