STEVE INSKEEP, host:

This is MORNING EDITION from NPR News. I'm Steve Inskeep.

A suicide car bomber attacked a convoy in the northern Iraqi city of Mosul. It's the kind of attack that's all too common in Iraq, and this time the target was a US diplomatic convoy. The attack killed four Americans. NPR's Anne Garrels joins us now from Baghdad.

Anne, how did this attack happen?

ANNE GARRELS reporting:

It was another suicide car bomb. It rammed the middle vehicle in a three-car convoy, killing a US diplomatic security agent attached to the US Consulate in Mosul as well as three private guards who were also part of the consulate security detail. This is the second attack on a diplomatic security team this month. On September 7th down in Basra, a roadside bomb killed four private American guards working for the US Consulate there.

INSKEEP: We're talking to NPR's Anne Garrels at a very busy time in Iraq. And, Anne, let's move next to Basra in the southern part of the country. That was seen as relatively calm, one of the calmest places in the country, but now we have these reports of British troops clashing with Iraqi authorities who are supposed to be their friends.

GARRELS: Yes, there are several. I'm just going to back up for a second because there are several things all going on at once at Basra, which makes it incredibly complicated. Basra is a Shiite city. There has been growing violence there as rival Shiite militias fight amongst themselves and now, as you know, with British troops. These competing militias come from Moqtada al-Sadr's al-Mahdi Army and the Badr Brigade, which is associated with the Supreme Council of the Islamic Revolution in Iraq, known as SCIRI. Now that's a leading member of the governing Shiite coalition.

These militias are now accused of infiltrating the police force and committing abuses. In August, a freelance journalist who wrote about this in an op-ed piece for The New York Times was picked up and later found shot dead. He was picked up in a police car, and yesterday, a second reporter who had been working for The New York Times in Basra was found shot to death after he had been picked up in a police car. In addition to this, you've got Sunni extremists who've been attacking Shiites down there, and it's a tinderbox now.

INSKEEP: Anne, this is the circumstance under which British authorities came to attack an Iraqi prison. What happened?

GARRELS: Well, it started on Sunday when British forces in Basra arrested three members of Moqtada al-Sadr's Mahdi Army on suspicion of terrorism. This prompted protests, and two British soldiers working undercover dressed as Iraqis got in a gunfight with the Iraq police. The police detained them. British vehicles headed for the police station where they were believed to be held. Sadr's people, backed by the police, called on the public to stop the British from releasing their men. There were violent protests. At least one British armored vehicle was set on fire. Finally British forces smashed a prison wall to free the two undercover soldiers, saying they feared for their lives. It turned out the two men had been moved elsewhere, as the British say they feared, and were being held by a militia. However, British officials this morning say that they've been able to rescue them.

INSKEEP: Anne, if we move beyond this specific incident, are the forces of the US-led coalition and the authorities who now control Basra still on the same side?

GARRELS: It would appear not. The British are now having real problems with a police force which they believe has been infiltrated by competing militias who are fighting against each other and against the British. We're seeing more and more of this kind of violence.

INSKEEP: NPR's Anne Garrels is in Baghdad. Anne, thanks as always.

GARRELS: Thank you. Transcript provided by NPR, Copyright NPR.