(CNN) At least two people were killed in an explosion outside a busy shopping mall in the southern Philippines Monday.
Cotabato City Police spokesman Christopher Lee told CNN there was a suspected "IED explosion" outside the South Seas Mall in Cotabato City on the island of Mindanao.
Another 34 people were injured in the blast, three of whom were in critical condition, local police spokesman Chief Inspector Rowell Zafra said.
Zafra added that a second, smaller improvised explosive device was discovered in the second-floor baggage area of the mall, and was detonated safely by authorities.
A lockdown that was put in place for the city after the bomb exploded has since been lifted, but additional troops have been deployed across Cotabato in a push to increase security.
Jewel Blake H. Lumasag, a local pastor who lives in Cotabato City, said he was on his way to the mall when the explosion hit. He told CNN police made him leave the area over fears there was another bomb.
In a Facebook post Monday, Cotabato Mayor Frances Cynthia Guiani-Sayadi called the blast an "act against humanity."
"I strongly condemn the bombing incident that happened in front of South Seas Mall today, a day before the New Year, the [sic] took away several innocent lives and injured dozen others," she wrote.
"This is not just another terroristic act but an act against humanity. I cannot fathom how such evil exists in this time of merry making."
Mindanao, a province in the far south of the Philippines at the borders of Malaysia and Indonesia, has long been plagued by terrorism and unrest.
In July, at least 10 people were killed when militants linked to the Abu Sayyaf terror group struck a military checkpoint with a car bomb.
The province is home to several Islamist insurgent groups, including Abu Sayyaf, which has been blamed for a number of attacks on civilians and Philippine government troops, as well as the kidnapping of several foreign nationals.
Abu Sayyaf -- alongside the Maute group, another Mindanao-based terror organization -- was responsible for the invasion and occupation of Marawi, the country's biggest Muslim-majority city, in 2016.
Earlier this year, Philippines President Rodrigo Duterte approved the Bangsamoro Organic Law (BOL), creating an autonomous region in majority-Muslim areas of Mindanao.
The law, which gives greater independence and autonomy to Muslims in the predominantly Catholic Philippines, is the culmination of decades-long peace negotiations between Mindanao-based rebel groups, including the Moro National Liberation Front (MNLF) and the Moro Islamic Liberation Front (MILF) and the national government, according to CNN Philippines.
Duterte has said that he would not negotiate with Abu Sayyaf or other Islamist militant groups.