Colombian President Juan Manuel Santos is offering a $35,000 reward for information leading to the capture of those who set off a bomb Saturday in a luxury shopping mall.
Three people were killed and nine wounded in the blast in the women's bathroom at Centro Andino in central Bogota.
"In the face of cowardly acts like yesterday’s, Colombians must unite and be supportive," Santos said Sunday. "We will not allow what has been achieved so far to be stopped by a handful of extremists, cowards or those who do not want the reconciliation of the Colombian people."
The bomb blew up next to a toilet while the mall was packed with shoppers getting ready for Father's Day.
Those killed included a young French woman who was volunteering at a school in a poor Bogota neighborhood.
No one has claimed responsibility for the blast. Suspicion has fallen on the country's second rebel group - the National Liberation Army - which refused to join the FARC rebels in signing a peace deal with the government.
But the ELN, which is negotiating peace, condemned the bombing and attacks on civilians. It was behind a February attack that killed a policeman.