Costa Rican authorities say they have seized a small plane carrying $1.5 million in cash and 880 pounds (400 kilograms) of cocaine. Officials also detained four Costa Rican and two Mexican men.

Costa Rica's Judicial Investigation Police said in a statement Monday the plane traveled from Guatemala and landed at a clandestine landing strip in Guanacaste province, where four men were ready to load the drugs when officials arrested them.

Officials say the men had planned to fly the small plane back to Guatemala and then to Mexico.

They say the Sunday seizures and arrests are the result of a two-month investigation.

Mexican drug traffickers have increasingly been using Costa Rica to smuggle U.S.-bound drugs.