Afghan authorities say suicide bombers have killed nearly 30 people in a usually peaceful city in southwestern Afghanistan.

More than 70 others were wounded in Tuesday's attacks in Zaranj, the capital of Nimroz province. Officials say most of the casualties are civilians. Security forces are also among the dead.

Police say at least three suicide bombers carried out a series of coordinated attacks in different parts of the city, including a busy marketplace. Security forces detained three other attackers and shot and killed five before they could detonate their explosives.

There was no immediate claim of responsibility.

Tuesday's attack is one of the worst in Nimroz province this year.

The province province borders Iran and Pakistan and is usually peaceful, although it has seen a recent increase in violence. On Saturday, an Afghan police officer killed 11 of his colleagues in the Dilaram district of Nimroz.