Police sources said the officers were killed on Friday when the vehicle in which they were travelling was hit by explosives.
It is the worst attack on security forces since Gustavo Petro was sworn in as Colombia's first left-wing president less than a month ago.
Images obtained by the newspaper El Tiempo showed bodies strewn around a police pickup truck.
Eight deaths were initially reported but the government later revised down the figure, to seven dead and one injured, BBC reported.
According to the national police and attorney general's office, three of the officers who were killed were aged 20 or younger.
Petro condemned the attack, calling it "a clear act of sabotage against peace" in a tweet.
Late on Friday, he travelled to the regional capital of Neiva for a security meeting.
No group has said it was behind the attack, but Colombia's Blu Radio pointed the finger at guerrilla groups operating in the area.
And security sources have said that dissidents from the now disbanded communist guerrilla group, Farc operate in the area, Reuters news agency reported.
Petro was elected on a radical manifesto to fight inequality by providing free university education, pension reforms, and high taxes on unproductive lands - a departure for Colombia that had previously voted only conservative presidents into office.
He also pledged to fully implement a 2016 peace deal that ended a 50-year-long conflict with Farc and to seek negotiations with the still-active National Liberation Army (ELN) who are widely seen as the last organized guerrilla group operating in Colombia.
ZZ/PR