The attack happened at sundown Wednesday as the troops were marking the end of the first day of fasting during the Muslim holy month of Ramadan.
It was the latest in a string of brazen strikes by militants that has killed more than 2,600 people since the start of April.
Gunmen launched their assault on the army checkpoint near the town of Barwana, which lies across the Euphrates River from the town of Haditha, about 220 kilometers (140 miles) northwest of Baghdad.
Barwana’s mayor, Meyasser Abdul-Mohsin, said three soldiers were killed and four were wounded in that attack.
The attackers then made their way to a trailer not far away that is used by special oil industry police assigned to protect a nearby pipeline. The men inside were sitting down to have the iftar meal that breaks the daytime Ramadan fast at sunset, Abdul-Mohsin said.
The gunmen shot up the trailer and then set it on fire before making their getaway, the mayor said. Eleven police were left dead, with some of their bodies badly burned and making them difficult to identify, he said.
“This is a crime carried out by terrorists during iftar on the first day of Ramadan,” Abdul-Mohsin said. “It just proves what a cowardly act it is.”
A security official in nearby Haditha gave a similar account and confirmed the death toll. He spoke on condition of anonymity because he was not authorized to release the information.
There was no immediate claim of responsibility. Extremist militants, including al-Qaida’s Iraq arm, frequently target security forces and the country’s vital oil infrastructure in an effort to undermine the government.
Insurgents launched more attacks Thursday.
Iraqi security forces clashed with three militants who tried to ram their explosives-laden car into a police station outside the Anbar provincial capital of Ramadi, councilman Talib Hamadi said. Two policemen were killed and four others were wounded in that attack, though security forces managed to kill the would-be bombers before they were able to detonate their explosives, Hamadi said.
Elsewhere, a parked car bomb went off Thursday morning near a courthouse in the northern city of Tuz Khormato, wounding 30 people, mayor Shalal Abdool said. Tuz Khormato sits in a band of territory contested by Arabs, Kurds and Turkomen about 200 kilometers (125 miles) north of Baghdad.
Another parked car bomb exploded in a village outside the nearby ethnically disputed city of Kirkuk, wounding seven civilians, provincial police chief Maj. Gen. Jamal Tahir said.
BA/BA