Detectives investigating the attempted murder of a police officer in Northern Ireland have made two arrests.
Men aged 25 and 34 were detained in Belfast last night after the constable discovered a bomb under his car at his home in the city on Sunday.
Senior officers have said the attack could have killed the policeman's wife and two young children.
Police were on high alert yesterday after dissident republicans attempted to murder the officer with a car bomb and a second explosive device was discovered near a police station.
The bomb was placed under the car of the off-duty constable in east Belfast, Police Service of Northern Ireland assistant chief constable George Hamilton said.
"If that officer had not checked under his car we would have been looking at a murder or multiple murders," he said.
In a separate incident, a pipe bomb was found close to the gates of a police station in the town of Tandragee in Mid-Ulster, near the homes of elderly residents.
The booby-trap device in Belfast was defused in a controlled explosion by the army.
It was recovered from under the officer's car partially intact and police hope forensic tests on the remains could identify those who made and planted it.
Mr Hamilton said he was linking the attack to "anti-peace" dissident republicans, who have already murdered two police officers.
"We are hopeful that it will provide useful evidence," he said.
"The fact that it was discovered and it didn't ignite means that we obviously have a starting point forensically."
Police have been warning for months that republican militants remain determined to kill members of the security forces.
On November 1, prison officer David Black was shot dead as he drove along the M1 motorway on his work to work at the high-security Maghaberry prison in Co Antrim, which houses dissident inmates.
A group styling itself the "new IRA" claimed that attack. The faction was formed in the summer when several splinter groups joined forces.
Less than two weeks later, an under-car booby-trap bomb was found lying on a road in west Belfast. It is believed to have fallen from a soldier's car.
In recent months police in Belfast and Londonderry have recovered horizontal mortars capable of piercing the armour of police vehicles and causing multiple fatalities.
During the past year, police have arrested 115 people suspected of dissident republican activity, and 35 have been charged. Sixty-four officers have been forced to leave their homes during the past five years because of intelligence that they were being targeted for potential attack.
Many others have had additional security measures like bulletproof glass installed in their homes.
The chairman of Northern Ireland's Police Federation said he would be seeking a meeting with PSNI chief constable Matt Baggott to discuss officers' personal security and the recruitment of extra staff.
Terry Spence said more needed to be done to ensure officers' safety at home and at work.
Northern Ireland Office Minister Mike Penning said everything Mr Baggott and Stormont Justice Minister David Ford had asked for to combat violent groups had been provided and he joined Mr Ford in condemning the latest attack.
"Those who are responsible offer nothing except terror and misery, not just to this police officer and his family but to his neighbours and the wider community," he said.