Philippine military officials say at least three people have been killed and 11 others wounded in a grenade attack by suspected communist insurgents in the country's south.

Authorities said rebels on motorcycles threw the grenade into a bakery in Nabunturan town before dawn Thursday.

A military spokesman, Major Armand Rico, said authorities believe New People's Army (NPA) guerrillas were behind the attack. Officials suspect it was a response to the shop owner's failure to pay extortion money, known as "revolutionary taxes," to the rebels.

The roughly 5,000-member New People's Army has been waging a Maoist rebellion in the region for 39 years and is on a U.S. list of terrorist organizations. 

Some information for this report was provided by AFP, and Reuters.