A grenade attack on a mosque in the troubled southern Philippines killed two people early Wednesday, authorities said, just days after a deadly Catholic cathedral bombing and a vote backing Muslim self-rule.
"A grenade was lobbed inside a mosque killing two persons and wounding another four," regional military spokesman Lieutenant Colonel Gerry Besana told AFP of the attack in Zamboanga City.
The victims were sleeping inside the mosque at the time of the attack on the insurgency-plagued island of Mindanao, which is home to the Philippines' Muslim minority.
The blast comes as the country was on high alert after a cathedral bombing that killed 21 people at Sunday mass on the remote, Muslim-majority island of Jolo.
The Islamic State group claimed responsibility for the cathedral blast.
Philippine authorities initially said it was not a suicide attack, but on Tuesday President Rodrigo Duterte contradicted them saying one of the bombers had blown himself up outside the cathedral.
Besana told AFP it was too early to say whether the mosque blast was retaliation for the cathedral attack, adding police were hunting for those responsible.
The attacks have interrupted the joy spurred by voters' decisive approval of giving Muslims in the south more control over their own affairs, which sparked hopes of quelling long-time separatist violence.
Rebels and the government in Manila have expressed hope the new so-called Bangsamoro area will finally draw the investment needed to pull the region from the brutal poverty that makes it a hotspot for radical recruitment.
However, hardline factions aligned with IS were not part of the decades-long peace process with the nation's largest separatist group, the Moro Islamic Liberation Front, that culminated January 21 with the resounding approval of a new Muslim led-region in the south.
Jolo, which is home to hardline Islamist factions, is the only area in the southern Philippines that voted against the Bangsamoro. Its leader came out publicly against the region and even asked the nation's top court to halt the vote.
The grenade attack on Wednesday drew immediate condemnation from authorities.
"There is no redeeming such blasphemous murder. It is the highest form of cowardice and obscenity to attack people who at prayer," said regional leader Mujiv Hataman.
"We call on people of all faiths... to come together to pray for peace."