Police use batons and tear gas to control the crowds in the town of Popayan
Thousands of Colombians have taken part in violent protests in several cities to demand the return of money invested in disreputable financial schemes.
Police used batons and tear gas to control angry investors and curfews were declared in several cities.
In Popayan in the south-western department of Cauca, 2,000 depositors stormed an investment firm's offices.
In Pereira, in Risaralda, police caught two men hurrying out the back door of a scheme's office with suitcases of cash.
They offered one of the cases to the police to let them go.
The BBC's Jeremy McDermott in Medellin says they are now in custody and that is the safest place for them, as conned investors have threatened to lynch them.
Many savers have lost everything
It is not clear how much money overall may have been scammed but for many individuals it was most of their life savings.
"Everybody was full of hope for December, for the holidays. The people thought their lives would change," one man who said he had lost the equivalent of $1,500 told AFP in Popoyan.
Hundreds gathered outside a company called DRFE in the town of Armenia, among them Luis Alberto Sierra who told Caracol TV he had lost some $17,000.
"I mortgaged my house, invested all my savings," he said.
Marta Aristizabal in Cali told Caracol TV she had lost around 30m pesos ($13,000).
"It's so uncertain, we've heard the company's bankrupt, we don't know what's happened."
Angry investors in several regions ransacked DRFE offices and clashed with police sent to restore order.
In the city of Pasto, in the department of Narino, local television showed depositors looting local businesses.
Colombia's vice-president told investors nothing was free in this world
In Popayan, police fired tear gas to disperse people trying to break into the investment company's office to recover their money.
The people behind a pyramid scheme in Santander de Quilichao disappeared, leaving a note stuck to the doors taunting the investors for having been duped.
It said: "Now for being stupid and believing in witchcraft you will have to work much harder to recoup the money you gave us."
The office of another pyramid scheme had a greetings card stuck on the door which read: "We wish you a sad Christmas and a shameful New Year."
Investigations into such schemes have been under way for several months but Colombian President Alvaro Uribe called for intensified action against companies suspected of defrauding people.
He has also urged Congress to pass stiffer laws to increase the penalties for investment scams.
Vice-President Francisco Santos warned people to avoid pyramid schemes.
"When someone promises to double your money in six months they are trying to trick you," he said. "Nothing is free in this world and that is not going to change."
A number of bogus companies have vanished in recent months after promising depositors interest rates as high as 150%.
Our correspondent says some of the schemes have actually paid out money to investors to launder drug profits.
Pyramid investment schemes are said to be often more popular than regular savings accounts in Colombian banks, which charge high fees.