Two bombs exploded Monday in a southern Thai town, killing two policeman and injuring several people, police said. Two other bombs were found before they could go off.

The blasts in Pattani (search) came a day after unidentified assailants set fire to 21 schools and raided a military armory, killing four soldiers in neighboring Narathiwat (search) province. The government blamed Islamic separatist insurgents for those attacks.

On Monday, two policemen were killed when they were trying to defuse a bomb planted on a motorcycle, parked in a lot of the Diana shopping mall, a police spokesman said.

Another explosion occurred at a police box in a public park, injuring one officer, he said.

The independent ITV television station said the device was a time bomb set to go off at 3 p.m. local time.

A third bomb was found in a telephone kiosk and was defused without incident, the police spokesman said. He said a fourth bomb was found in a gasoline station and police were trying to disarm it. No other details were known.

Four southern Thai provinces including Narathiwat and Pattani are the only Muslim dominated parts in the predominantly Buddhist Thailand (search).

The provinces, bordering Malaysia, have long been the scene of an Islamic separatist insurgency that died down in the late 1980s. It resurfaced two years ago with attacks on government and security force targets that have left more than 50 policemen and soldiers injured.

The area is about 650 miles south of Bangkok.