An important gas pipeline has been blown up in northern Iraq.
There have been regular attacks on Iraqi infrastructure
The resulting fire was so huge the glow could be seen in the night sky in the town of Kirkuk, 30 kilometres (20 miles) away, say reports.
The attack is expected to cause disruption to production at Iraq's largest oil refinery, officials say.
It comes amid an upsurge in violence in the north of the country, in which two US troops were reportedly killed on Sunday by an angry lynch mob.
Eyewitnesses in Mosul, said two US soldiers were shot, then dragged from their car in broad daylight and beaten with bricks and stabbed by a group of young Iraqi men.
Some witnesses said the two soldiers had had their throats cut, but the US military would not confirm this.
"We will not be ghoulish about this," Brigadier General Kimmitt told reporters in Baghdad.
"We have an ongoing investigation. It is not our policy to discuss the specifics of injuries sustained by soldiers and this is not a good place to discuss these kind of things."
The dead men, from the 101st Airborne Division, had been on patrol in Mosul, 400 kilometres (250 miles) north of Baghdad.
The town had been considered fairly peaceful. But there are fears that the Iraqi insurgency is spreading northwards, widening from its stronghold in the so-called Sunni Triangle in central Iraq.
In the latest attack in Mosul, a US soldier was injured on Monday by a roadside blast.
In other developments:
In Kirkuk, the North Oil company told AFP news agency an explosive device caused the pipeline fire.
- Coalition officials suspend civilian flights into Baghdad airport after a missile attack on a plane on Saturday. Military flights will still operate.
- Sunni Muslim leader Adnan al-Dulaimi calls for a week-long ceasefire by Iraqi insurgents to allow for a peaceful celebration of the Eid al-Fitr festival that marks the end of the fasting month of Ramadan.
- The first batch of 106 Iraqi police complete training in Jordan, which has offered to train 32,000 police over the next two years.
- The Baghdad offices of Dubai-based satellite TV al-Arabiya station are closed by the authorities for "incitement to murder" after broadcasting calls by Saddam Hussein for attacks on Governing Council members.
The attack has halted supplies of gas from Jambur oil field to a power plant in the town of Baiji.
That in turn is likely to cause disruption to oil production at the refinery in Baiji - Iraq's largest - the head of the oil company's fire department reportedly said.