More than four tons of marijuana were seized last week in a series of maritime incidents in which two drug-laden ships ended up sinking, the Colombian navy has said. A total of three vessels were intercepted, with at least one sinking as it tried to elude navy ships, the navy said in a statement Saturday.  

The navy said the ships were carrying marijuana worth about $29 million and posted video of officers unloading packages containing the drugs. 

Captain Wilberth Jair Roa Wilches said the first incident occurred when a Colombian Navy aircraft located a boat that was navigating at a "high velocity" in the north Pacific area. Because of bad weather, the boat took on a lot of water and ended up sinking. Officials rescued the two people who were on board and recovered about 5,000 pounds of marijuana from the vessel, the navy said.

In the second incident, officials said a high-speed ship was detected in the central Pacific. The boat, with two people on board, was intercepted and officials said about 2,000 pounds of marijuana, in more than 1,000 packages, was seized. 

In the last operation, units of the Pacific Naval Force detected a vessel manned by three individuals about 50 nautical miles off the coast of Bahía Solano. The boat "carried out evasive maneuvers to flee" but was unable to do so and ended up sinking, officials said. Officers rescued the three people from the water and gave them first aid. Later, 46 packages that were adrift in the sea were recovered, holding about 2,500 pounds of marijuana, the navy said.

In all, seven arrests were made and more than 700,000 doses of the drug were seized, officials said. The suspects face multiple charges, including trafficking, manufacturing and carrying narcotics.

The Colombia navy has been busy intercepting drug-laden vessels off the coast. Last month, a semi-submersible vessel carrying nearly 1,000 packages of cocaine was intercepted off the coast of Colombia. That came about a week after officials seized another "narco sub" carrying two dead bodies and a huge haul of drugs in the same region.

In:
• Marijuana
• Colombia

Stephen Smith is a senior editor for CBSNews.com.