Suspected left-wing rebels have killed at least seven police officers in a clash over coca eradication efforts in Colombia, the government says.
The drive against coca could lead to further clashes with rebel groups
The officers were guarding workers involved in an operation to destroy cocaine laboratories and the plants used to make the drug, officials said.
A worker was also hurt in the incident at the Sierra Macarena National Park, 170km (100 miles) south of Bogota.
The president called the police heroes, and sent military reinforcements.
"They died in the line of duty liberating this park from the claws of terrorism," Alvaro Uribe said.
Some 2,000 troops, along with 1,500 police officers, were sent to the national park earlier this month after rebels killed 29 soldiers working to destroy coca near the park.
President Uribe vowed to wipe out coca in the region after the attack, which was blamed on the country's main rebel group, the Revolutionary Armed Forces of Colombia (Farc).
The illegal drugs trade is a key source of funding for the Marxist insurgent group.
Rebels have moved into national parks to grow coca because environmental concerns block chemical spraying within them.
For Operation Macarena, 900 farmers have been employed to pull the plants up by hand from around 4,600 hectares of land inside the park.
Gen Jorge Daniel Castro, the National Police chief in charge of the operation, said it was risky work because the park is "Farc territory".