Colombian police were continuing to investigate the murder of 12 youths found dead after apparently accepting money to play a football match.
The decomposed bodies of the young men appeared in an estuary near the port city of Buenaventura earlier this week.
They were found floating by fishermen, with their hands tied behind their backs and each one shot in the head.
Authorities say the killings could be drug-related, the work of a death squad or one of Colombia's armed groups.
Buenaventura, 350km (215miles) southwest of the capital Bogota on the Pacific Coast, is on a main drugs smuggling route used by leftwing rebels and outlawed rightwing paramilitaries.
Relatives of the victims said the young men had agreed to go on a minibus to the supposed game on Tuesday, after accepting an offer from persons unknown.
Police said 10 of the victims were aged between 18 to 24-years-old but two were aged 15.
Forensics were examining the bodies to determine whether the victims had been tortured.
Investigators said it remained unclear who was behind the massacre.
City's Mayor Saul Quinones said the killings, which have shocked local people, were likely to be linked to the struggle for control of the drugs trade.
He said three out of every four murders in the city were drug-related.
A curfew has been declared in some of the city's more troubled neighbourhoods.