LAW enforcers beefed up security in parts of the Mindanao region after blasts injured at least 21 people in Cotabato province on the eve of President Rodrigo R. Duterte’s planned visit on Monday.

“The series of separate explosions in Cotabato last night has prompted police units in the area to step up target-hardening measures to protect soft targets, vital government installations and public establishments against similar hostilities,” Philippine National Police officer-in-charge Lieutenant General Archie Francisco Gamboa said at a briefing on Monday.

“At the same time investigations are under way to possibly identify the suspects behind these explosions,” he added.

The military and police “have the situation under full control,” Cotabato City Mayor Frances Cynthia Guiani-Sayadi said in a social media post. “While we are receiving reports from our authorities, I am appealing to all our constituents to remain calm.”

Also on Monday, the Justice department ordered the National Bureau of Investigation (NBI) to help probe the bombings.

In an order, Undersecretary Adrian Ferdinand S. Sugay ordered NBI Director Dante A. Gierran to build up a case on the bombings in Cotabato and Maguindanao.

The initial explosions took place in Tantawan and Quezon Avenue in Cotabato City before 6 p.m. on Sunday. Two more followed in Libungan town in Cotabato province, and another in North Upi, Maguindanao province.

Authorities found another improvised bomb and detonated it on Monday morning, according to the Philippine Army.

The military said seven of those hurt were part of a military group that was helping to secure the area for a land distribution ceremony that Mr. Duterte was supposed to attend. Cotabato City is the seat of the new Bangsamoro Autonomous Region in Muslim Mindanao.

Seven other civilians were also reported hurt.

In Libungan, the first explosion took place near the town hall and the other at a store selling liquefied petroleum gas.

A 60mm mortar was used in the first and second blasts in Libungan, according to a bomb team.

“The people of Libungan are condemning the incident to the highest order but at the same time we remain calm and civil,” Vice-Mayor Ronaldo B. Pader said by telephone.

Authorities have leads on the perpetrators, Mr. Pader said, declining to give more details pending the investigation.

Seven people were hurt in the Libungan blasts, with one seriously wounded, he said.

The two reported injured in Maguindanao had not been verified.

Both Ms. Sayadi and Mr. Pader said authorities have tapped village-level peace and order forces to reinforce security. — Carmelito Q. Francisco, Maya M. Padillo and Vann Marlo M. Villegas

RELATED ARTICLESMORE FROM AUTHOR