By Ghazwan Hassan
TIKRIT Iraq (Reuters) - Sunni insurgents overran parts of the city of Samarra in northern Iraq early on Thursday, bringing them within striking distance of a Shi'ite shrine that was previously the trigger for sectarian war.
The offensive is part of an escalating war between Iraq's Shi'ite-led government and militants who have been regaining ground and momentum over the past year, particularly in the west of the country bordering Syria.
The Sunni militants blew up a police station around 25 km south of Samarra overnight, security sources said, killing several policemen before advancing on the city in pick-up trucks, raiding checkpoints on the way.
After entering the city from both east and west, they seized control of the municipality building and university, raising the black flag of the Sunni militant 'Islamic State in Iraq and the Levant' (ISIL) over both buildings, police said.
They also occupied Samarra's two largest mosques and announced the "liberation" of the city via loudspeaker, urging residents to join their jihad (holy war) against the government.
Officials said the militants had reached within about two kilometers of the Askari shrine, whose destruction by insurgents in 2006 touched off the worst bout of Sunni-Shi'ite bloodletting to follow the U.S.-led invasion of 2003.
"People are terrified. We haven't slept since the attack started at 3.30 am," resident Mustafa al-Sammaraie told Reuters. "I saw some of them pass in front of our house: some gunmen with long beards and Afghan dress on a pickup truck."
A curfew was imposed on the city and reinforcements were sent up from Baghdad, arriving shortly after noon on Thursday. A source in Samarra hospital said the bodies of six policemen had been brought in, and 24 other people were wounded.
A security officer in the Salahuddin operations command described the situation in the city as dire and said the rebels, armed with RPGs and snipers, were targeting command centers near the Askari shrine, which is protected by three security belts.
In January, the Sunni Islamist insurgents overran two cities in the western province of Anbar, which borders the region of Salahuddin where Samarra is located.
"The security situation is so fragile now in Salahuddin and we don't rule out that the insurgents will expand further," said provincial council member Sabhan Mulla Chiad. "I am not optimistic at all."
A curfew was also declared in Baiji, around 100 km northwest from Samarra, in anticipation of a further advance by the insurgents, while clashes erupted in the town of Sulaiman Beg, which was briefly overrun by militants earlier this year.
Chiad said that even if the Iraqi army succeeded in re-taking Samarra, the insurgents would simply pull back to the outskirts, and other parts of Salahuddin would remain under threat.
In March, gunmen dressed in military uniform broke into Samarra city council and court house, holding the facility for four hours until police and army regained control.
(Additional reporting by Isra al-Rubei'i and Raheem Salman; Writing by Isabel Coles; Editing by Gareth Jones)