The Philippines Police killed 13 suspected drug dealers and arrested over 100 people during a 24-hour operation intended to crack down on the narcotics trade, Reuters reported on Thursday.

Police forces in Bulacan province conducted about 60 “buy-bust” operations in nine towns, Bulacan police chief Romeo Caramat said. A buy-bust is an operation in which undercover police officers buy narcotics and then arrest the seller.

“These operations are part of our stepped-up campaign against drugs and all other forms of criminality in the province,” Caramat said. “Unfortunately, 13 of the suspects were killed when our officers fired in self defence.” He claimed that the suspects were armed with concealed guns and started firing when they realised they had been trapped.

Caramat said that the police arrested over 100 people and seized 19 firearms and about 250 packets of suspected drugs during the 24-hour operation.

Philippines President Rodrigo Duterte was elected in 2016 after promising that 1,00,000 people would die in his war on drugs. In October 2017, he said that he was prepared to shoot criminals himself to combat the drug menace. Duterte withdrew the police from his anti-drug campaign on October 11 after they were accused of human rights abuses, but then threatened to bring them back.

In August, the police killed 32 people in a day in Bulacan. In February this year, they killed 10 more suspected drug dealers. According to government figures, the police have reported killing 3,900 “drug personalities”, while nearly 2,290 have died in “drug-related killings” until November 2017.