MANILA -- A grenade explosion damaged a Catholic church in Jolo town in Sulu province Sunday morning, a police official said.

Acting Autonomous Region in Muslim Mindanao (Armm) police director Bienvenido Latag said a grenade exploded inside the compound of Mount Carmel Cathedral in Barangay Walled City in Jolo around 5:40 a.m. No one was hurt.

“There were no reported casualties but the explosion damaged some window jalousies," said Latag in a radio interview.

Latag said police are still conducting investigation on whether or not the incident is connected to the start of the election period.

The election period started Sunday, January 10. The government implemented a total gun ban on Sunday, ahead of the general election on May 10 this year.

Last year, two grenade blasts also rocked the same church.(Kathrina Alvarez/Sunnex)