Suspected Islamist gunmen killed four policemen at the family home of Tunisia's interior minister, officials said Wednesday, describing it as a "revenge" attack for progress in the fight against jihadists.
The overnight assault on Lotfi Ben Jeddou's home at Kasserine, in the western border region, was reminiscent of violence in 2013, when two politicians were assassinated and jihadists killed 20 security force members.
"We went into this battle knowing what to expect," Prime Minister Mehdi Jomaa told reporters.
"They might hurt us but they won't prevail. We will defeat them," he added as the president declared a day of national mourning.
The assault by about a dozen gunmen shortly before midnight left dead four policemen and wounded two, interior ministry spokesman Mohamed Ali Aroui told AFP.
"The terrorist group had infiltrated from Mount Salloum to target the house of the interior minister," Aroui said on national television.
The mountain, which neighbours Mount Chaambi on a range bordering Algeria, had been declared a military zone in April as the authorities moved to tighten the noose around jihadists.
According to a security official in Kasserine, the four policemen were in a garage next to the house, where they were ambushed and killed.
Two other policemen, who had been outside and exchanged fire with the assailants, were wounded and hospitalised, according to the same source.
One of them, Walid Mansour, told Mosaique FM radio that attackers had arrived in a vehicle and shouted "Allahu akbar!" (God is greatest) before opening fire.
It was not immediately clear who, if anyone, was in the house at the time of the attack. The minister himself normally stays in the capital while his wife and children live in Kasserine.
Speaking on Radio Shems FM, the interior minister said Tunisia was "still at war with terrorism and we should expect some losses."
Ben Jeddou said the assailants were "experienced" and "trained to kill," adding that one of them had fought in Mali and another took part in a Mount Chaambi attack that killed soldiers in July 2013.
The assault, he said, was carried revenge for "a series of successes" of Tunisia's counter-terrorism forces.
Since late 2012, security forces have suffered numerous casualties in their fight against jihadists hiding out in the remote western region.
The authorities have linked the militants to Al-Qaeda but have failed to defeat them despite launching successive air and ground operations.
Aroui, the ministry spokesman, said the militants wanted to send a message to the security forces.
"But we will continue the war against terrorism," he added, calling for national unity in Tunisia and urging the media to "speak out clearly against terrorism."
Government spokesman Nidhal Ouerfelli condemned what he called "an odious and cowardly act."
The attack has sparked concern among Tunisians notably about how the gunmen managed to reach the minister's house without being stopped and despite security reinforcements around Mount Chaambi.
Tunisia is emerging slowly from a period of upheaval linked to violence blamed on Islamist militants following the 2011 revolution that toppled a decades-old dictatorship and touched off the Arab Spring.
Last year, more than 20 security personnel were killed in what the government says were "terrorism-related incidents," while the assassination of two leftist politicians sparked a full blown political crisis.
The crisis was averted when the majority Islamist party Ennahda stepped down in January in favour of a government of technocrats tasked with preparing fresh elections, as parliament approved a new constitution.
Jihadists have not claimed the attacks that have rocked Tunisia since the 2011 revolution, which also included two foiled suicide bombings at tourist sites last October.