Four martial arts gangs, armed with machetes and swords, fought pitched battles in the streets of East Timor over the weekend, leaving a police commander dead and dozens of houses burned to the ground, police said Monday.

The violence started late Friday in Ainaro, about 130 kilometers north of the capital, Dili, and spread to another village before fighting largely ended Monday, said Ainaro Police Commander Rarquimino Ramos. Ramos said a police commander was killed by unidentified men outside his home in Ainaro and that seven others, including three gang members, were missing. Fifty-three homes were also burned down. Clashes spread on Saturday to Baucau, about 128 kilometers east of Dili.

"Martial arts groups have been fighting one another for a long time," Ramos said. "The government needs to pass laws that regulate these groups because they are always stirring up trouble. People are scared the fighting will start again."

It was unclear what sparked the fighting, but Ramos said it was likely due to long-standing rivalries. Police have sent reinforcements to the villages and arrested more than 50 people, he said.

The fighting does not appear to be connected to pro-Indonesian militia groups, which along with the Indonesian military were blamed for killing 1,500 people and destroying much of the half-island before and after voters approved an independence referendum in 1999. The country became independent in May 2002.

There are dozens of martial arts groups in East Timor, who combine elements of kung fu, karate and taekwondo. Groups typically face off in sanctioned competitions but in recent months have increasingly fought pitched battles sparked by petty insults or personal grudges.

In June, four people including a 70-year-old man were killed when two martial arts groups clashed in the village of Urahu.