JOHANNESBURG (Reuters) - About 100 people ransacked shops in Johannesburg overnight, police said on Monday, in the latest of a wave of looting incidents in South African cities.

Doors and windows were smashed in, and food and other items were strewn on the floor in stores believed to belong to immigrants in Jeppestown, an area in the central business district, a Reuters witness said.

"We've been stuck inside here until the police came," Abdul Ebrahim, a Somali shop owner, said after emerging from his store, where a number of his colleagues had barricaded themselves.

"No one told us what they were looking for," he added when asked why the mob had attacked his shop.

At least one person was arrested.

"We are following up on leads and we are expecting to make more arrests," police spokesman Brigadier Mathapelo Peters said.

She said she did not know the nationalities of the shopkeepers and police were waiting for owners to come forward, so that they could open cases of violence and damage to property.

Similar incidents have taken place in Pretoria this month, but police have been reluctant to characterize the attacks as being directed against foreigners.

Anti-immigrant violence has flared sporadically in South Africa against a background of near-record unemployment, with foreigners being accused of criminal activity and taking jobs from locals.

Home Affairs Minister Malusi Gigaba last week acknowledged violence had flared up against foreigners this year, saying that "unfortunately, xenophobic violence is not new in South Africa."

On Friday, police fired tear gas, water cannon and rubber bullets to disperse marches by hundreds of anti-immigrant protesters in Pretoria, after mobs looted stores believed to belong to immigrants. More than 150 people were arrested.

(Reporting by Nqobile Dludla; and Dinky Mkhize; Editing by James Macharia and Mark Trevelyan)