Jakarta – Security forces mistakenedly opened fire on a crowd of ethnic Madurese migrants and local Malays in Indonesian Borneo killing four people and injuring three others, an official said Monday.

The incident Sunday happened when a group of security forces arrived in Karimunting village in the troubled Sambas district following a report of a dispute between Madurese and Malays in a Madurese neighbourhood.

They opened fire prematurely, a local official said. "There was a misunderstanding by the security when they saw Malays and Madurese together in a Madurese neighbourhood ... and four people were killed," Burhanudin, an official at the Sungairaya sub-district told AFP by phone.

The Antara state news agency reported however some homes had been torched before the shootout between the security forces and residents armed with homemade muskets.

"There were shootings among the security and the mob who had been attacking. Four people were killed from the crowd in the incident," West Kalimantan police chief Colonel Chaerul Rasyid was quoted by Antara as saying.

Three of the victims were Malays and the other a Madurese man. The bodies and the three injured were taken to the Dr. Aziz Hospital in Sambas district's main town of Singkawang.

"They might have gone outside (standard operating) procedures, but all that is currently being investigated by the police," Burhanuddin said, adding several were being questioned by police.

The shooting brought the death toll to five in the Sungairaya district since the first clashes there broke out two weeks ago. Almost 100 homes have been burned.

Violent clashes pitting the Madurese migrant community against Malays and Dayaks erupted in the Sambas district in West Kalimantan province in mid-January.

The violence, most of it directed against Madurese settlers there, has included beheadings and ritual cannibalism, with over 200 people killed and about 29,000 driven from their homes to refugee camps.