MANILA — A grenade was lobbed into a mosque in the southern Philippines before dawn on Wednesday, killing two Muslim religious leaders, in the second attack in days on a place of worship in the restive south, officials said.
The attack, in the city of Zamboanga, occurred three days after a bombing at a cathedral on the nearby island of Jolo, which killed 20 people outright. More than 100 people were wounded in that attack, one of whom died on Tuesday, bringing the death toll to 21.
The police said it was too soon to identify a motive for the Wednesday mosque attack. They said the possibility that it was retaliation for the Jolo bombing could not be ruled out, but they also cautioned against speculation. The southern Philippines, which unlike the rest of the mostly Roman Catholic country has a Muslim majority, has long been plagued by insurgencies.
The Islamic State has claimed responsibility for the Jolo attack, which it said was carried out by suicide bombers.
Some security officials initially blamed Abu Sayyaf, a local Islamist group, and said the two blasts at the Cathedral of Our Lady of Mount Carmel had probably been set off remotely, using a cellphone. Suicide attacks are rare in the Philippines.
But on Tuesday night, President Rodrigo Duterte contradicted that version of events. He said he had been briefed by intelligence officials who told him the attackers were suicide bombers.
“That is really terrorism, and that is really suicide,” Mr. Duterte said. He said that a woman wearing a crucifix had detonated a bomb inside the cathedral, and that a male companion had blown himself up outside minutes later.
The Philippine military, by contrast, has said that bystanders saw a woman, presumably the female bomber, put a bag onto a pew and leave the cathedral shortly before the blasts.
Rommel Banlaoi, the head of the Philippine Institute for Peace, Violence and Terrorism Research, said the attacks in Jolo and Zamboanga suggested that a law granting autonomy to Muslims in the south — which voters approved last week throughout the southern part of the Mindanao island group, except in a small province dominated by Jolo — would not quickly lead to peace.
He noted that groups like Abu Sayyaf, some of whose leaders formed a coalition that declared allegiance to the Islamic State, were not included in the peace deal that paved the way for the autonomy law, which Mr. Duterte has signed.
And while Abu Sayyaf is now seen by many as a ragtag group of militants that specializes in kidnapping, its leaders have taken advantage of the region’s lawlessness to invite foreign jihadists to the southern Philippines, said Mr. Banlaoi, who has studied Islamic insurgents in the south for years. In a 2016 video, the Islamic State advised regional fighters who could not travel to Iraq and Syria to head to the southern Philippines instead.
“They have built capabilities to mount large-scale attacks like the Jolo bombings,” Mr. Banlaoi said. “Unless the Abu Sayyaf and other peace spoilers in the area are defeated, parts of the south will be under constant threat of violence.”
Foreign jihadists have collaborated with Abu Sayyaf operatives in the recent past, most visibly in the siege of Marawi, a southern Philippine city that a coalition of militants held for months in 2017.
Mr. Banlaoi said the Jolo cathedral bombing could embolden other groups to mount their own assaults, noting that thousands of troops had poured onto the island since the Marawi siege but that attacks had continued.
“We have learned lessons,” Mr. Banlaoi said. “But threat groups like the Abu Sayyaf are quicker to learn and faster to act than law enforcement.”
He said it was too soon to conclude that the mosque attack in Zamboanga on Wednesday was a response to the Jolo bombing, but he said it was clearly a possibility. “The nature of armed conflict in Mindanao will be more complicated if sectarian conflict is proven,” he said.
Zamboanga, a port city with a mixed Muslim-Christian population, has seen a number of terrorist attacks over the years. Militants linked to Abu Sayyaf have been known to frequent the area to scout for targets.
Among the first attacks carried out by Abu Sayyaf in the early 1990s was the bombing of a ship used by a Christian missionary organization that had docked in the Zamboanga area, which killed two American missionaries. Over the next decade, a string of attacks in the city left scores dead or injured.
The Philippine Army said two men had been seen acting suspiciously near the mosque, in the village of Talon-Talon within Zamboanga, before the blast on Wednesday. The men killed were identified as Habil Rex, 46, and Bato Sattal, 47, of the island of Basilan.
The local Ulama Council, a Muslim clerical body, condemned the attack as a “devilish, irrational and inhuman act.”
“We share the grief of the families who lost their loved ones and sincerely extend our condolences to them in the most comforting manner that a human being may,” the council said in a statement.
Mr. Duterte has responded to the Jolo cathedral attack by ordering the army to assault militant positions on the island. On Wednesday morning, the local army commander, Brig. Gen. Divino Rey Pabayo, said troops had raided the home of a local militant suspected of being involved.
A man identified as Ommal Yusuf was killed, and troops recovered a cache of weapons, the general said. But he said that two others, one of whom was suspected to be one of the key planners of the Jolo attack, had escaped.