Four migrants, including a baby, were killed as their boat capsized while trying to cross from Colombia to Panama, authorities confirmed on Thursday.
The migrants wanted to cross the river from the northern town of Necocli in the country's Antioquia region to Panama.
Carlos Camargo, the director of the Colombian Ombudsman's Office, said migrants trying to illegally cross the river with flimsy boats put their lives at risk.
"We are deeply saddened by the incident. National and local authorities should pay more attention to the situation of these people," he added.
Thousands of migrants who want to reach the US due to internal turmoil and economic inadequacies demand the opening of the Colombia-Panama border.
According to the immigration agreement between Colombia and Panama, some 500 people buy tickets to go to Panama by boat every day.
This year, over 19,000 irregular migrants reached the US by crossing the borders of the two countries.
*Writing by Gozde Bayar in Ankara