MANILA -- President Rodrigo Duterte, who is in Israel for an official visit, has been informed of the latest explosion in the south his spokesman said Monday.

Malacañang is "deeply saddened" by the blast that killed an 18-year-old man and wounded 14 others, Presidential Spokesperson Harry Roque Jr said.

The explosion in Isulan town, Sultan Kudarat was the second explosion in the area in a week. Three people died while 30 others were injured after an improvised bomb went off at a town fiesta on Aug. 28.

"We ask the residents to report anything suspicious to the authorities as we bring to justice all culprits behind this dastardly attack," Roque said in a statement.

Isulan was placed on lockdown since the suspect in the attack could still be inside the town, said Brig. Gen. Cirilito Sobejana, commander of the Army's 6th Infantry Division.

Police tightened security in the area said PNP chief Director General Oscar Albayalde.

"We are saddened by the casualties brought about by this cowardly act perpetrated by people hell bent on their nefarious goals without regard for the lives of civilians," Albayalde said.