Story highlights Almost 6,000 suspects have been killed

President's critic calls for impeachment

Manila, Philippines (CNN) A 6-year-old Manila boy killed in his sleep is among the latest victims in the ongoing violence against suspected drug criminals in the Philippines.

"There was a knock on the door," said Elizabeth Navarro, who is pregnant and already a mother of five at 29. "My husband said who's that? Then I heard two gunshots."

By the time Navarro realized what was happening, her husband, Domingo Mañosca, and son, Francis, were dead. The gunmen were gone, in what has become open season for anyone suspected of being tied to drugs.

Since taking power in June, President Rodrigo Duterte has waged a brutal "war on drugs." The crackdown has been linked to more than 5,900 deaths.

On Monday, one day after the latest killings, Duterte revealed he personally had killed drug suspects while serving as mayor of his hometown, Davao City.

JUST WATCHED Philippines president admits to killings Replay More Videos ... MUST WATCH Philippines president admits to killings 01:30