BAGHDAD - Iraqi authorities arrested four men on Tuesday in connection with a shooting spree a day ago that left 27 policemen dead, including two officers killed execution-style. The group was arrested in Salaheddin province, north of Baghdad, after a police raid, the interior ministry said in a statement on its website. A fifth man blew himself up when the police arrived, it added. “The police of Salaheddin, after receiving reliable intelligence about the location of the criminal gang who carried out the assassinations against the police officers in Anbar, raided the location and arrested four of them,” the statement said.

“One of the terrorists blew himself up when they were surrounded,” it added.

On Monday morning, suspected Al-Qaeda gunmen, some wearing army uniforms, raged through the western Iraqi city of Haditha, in Anbar province, in a pre-dawn shooting spree that killed 27 policemen.

The assault, launched at about 2:00 am (2300 GMT on Sunday), saw insurgents dressed in military uniforms simultaneously attacking two checkpoints in the east and west of Haditha before storming other security posts and raiding the homes of two officers.

Haditha is in western Sunni Arab Anbar province. It was one of several towns along the Euphrates valley that became Al-Qaeda strongholds after the 2003 US-led invasion that ousted Saddam Hussein.

However, in 2006, local Sunni tribes sided with the US military and unrest dwindled in Anbar as rebel fighters were ejected from the region.

Violence across the country is down from its peaks in 2006 and 2007, but attacks remain common. A total of 150 Iraqis were killed in February, according to official figures.