A boy was killed during violent protests in the Caribbean city of Colon on Friday over a new law allowing the sale of state-owned land in the duty-free zone next to the Panama Canal, authorities said.

The 10-year-old boy was shot once in the stomach and died at the Manuel Amadador Guerrero Hospital in the Caribbean city of Colon, emergency unit director Mariano Lopez said.

Lopez said that at least six other people were treated for gunshot wounds and several others for pellet wounds.

Anti-riot police used tear gas and fired into the air to disperse hundreds of people who burned tires and threw objects at police in Colon's downtown. The protesters began leaving the area after the confrontation with police. Authorities didn't return calls seeking comment.

Colon's Mayor Damaso Garcia declared a curfew Friday afternoon.

The rioting came a few hours after the National Assembly approved legislation permitting the sale of land in the duty-free zone to private companies already leasing land there to handle the import and export of goods. President Ricardo Martinelli signed the law hours later.

Protesters said the land is already being rented and it makes no sense to sell it. They said the government should instead raise the rent and invest the money in Colon, a poor and violent city.

"We do not want the land to be sold because these are assets that belong to Colon," said Felipe Cabezas, head of the Colonense Broad Movement. "Why sell if the country is not going through economic problems?"

The duty-free zone has about 2,000 companies that rent land and employ 30,000 people, according to authorities. The government estimates land sales could raise $2 billion over the next 20 years.