CHRIS UHLMANN: In the aftermath of bomb blasts in the Kenyan capital of Nairobi that killed six, police have arrested more than 650 people.
Nobody has claimed responsibility for the attacks that targeted two small restaurants and a local clinic in the highly populated area of Eastleigh.
It's an area most often referred to as "Little Mogadishu" because of its mostly Somali population.
I spoke to our Africa correspondent Martin Cuddihy a short time ago about the mass arrests.
MARTIN CUDDIHY: It's not uncommon for authorities here to arrest a couple of dozen people after a terrorist incident and then release quite a few of those. But to arrest more than 650, certainly this is the first time that that has happened.
As I say, it's likely that a lot of those people will be released but it's a sign that the Kenyan government is clamping down on terror. It introduced a new law last week (inaudible) all Somali refugees who are resident in Kenya to report back to refugee camps.
So this is just another indication that they are really determined to make sure that this doesn't get out of hand and that the terrorism that is taking place here is controlled.
CHRIS UHLMANN: And a radical Muslim cleric has been shot and killed. What can you tell us about him?
MARTIN CUDDIHY: Well that's right. Not sure if the two are related but Sheikh Abubakar Sharif has been shot dead on a road outside Mombasa. He'd been accused previously and appeared in court accused of being a recruiter for Al Shabaab. He's also been outspoken in his support for that terrorist organisation. Last year after the Westgate attack he was quite vocal in praising the men who carried out that attack.
In an interview last month he said that he thought his life was in danger. So it's not clear who has shot him but he and another man have been killed on a road outside the coastal city of Mombasa.
CHRIS UHLMANN: In recent days the Australian Government has recast its travel advice to say that Australians should reconsider their need to travel to Nairobi and Mombasa due to the high threat of terrorist attack, so it is a significant and rising problem in Kenya.
MARTIN CUDDIHY: Yeah that's right. There have been a number of small attacks since Westgate last year. Westgate was the big attack where 67 people, tourists, well-to-do Kenyans were shot dead in a shopping centre. Since then there have been a number of small attacks where one or two people have died.
But this series of bombs in the suburb known as Little Mogadishu here in Nairobi appears to be an escalation. And coupled with a couple of other incidents that have occurred where a man on Sunday died while he was making an improvised explosive device, and also a week ago police in Mombasa found a car packed with six improvised explosive devices - enough to bring down a multi-storey building, so Kenyan authorities are really frightened at the moment that something big is just around the corner.
So that's why we've seen this crackdown. That's why we've seen this 657 people arrested. And that's why probably why we've seen this radical cleric who's been shot dead on a road where- just when he was coming out of a court.
CHRIS UHLMANN: Africa correspondent Martin Cuddihy.