MANILA — One of the founding members of a Philippine lawyers’ group at the forefront of opposing President Rodrigo Duterte’s lethal war on drugs was gunned down on Tuesday, killed by three bullets as he was leaving his office for the night.

The attorney, Benjamin Ramos, 56, was the 34th lawyer killed since Mr. Duterte became president two years ago. His group, the National Union of People’s Lawyers, specialized in doing no-cost work for poor clients whose families have been targeted by the police, soldiers and death squads associated with the president’s drug war.

“We are shocked, devastated and enraged at the premeditated, coldblooded murder of our colleague and fellow people’s lawyer,” said Edre Olalia, a leader of the group. “We are disturbed and unbowed. These are dangerous times.”

Initial police reports said that Mr. Ramos had just finished work when he was shot by motorcycle-riding men near the central town of Kabankalan on Tuesday night. He was declared dead on arrival at the hospital.