In the gulf of Aden, on board the Canadian warship Winnipeg Friday morning, the first calls came into the bridge from the cargo ship Maria K, reports CBS News correspondent Sheila MacVicar.
"They are still shooting with rocket-propelled grenades," the Maria K radioed.
The Maria K, a Lebanese-flagged ship, was under attack by Somali pirates.
"This is clearly an act of piracy," the commander of the HMCS Winnipeg Craig Baines told MacVicar. "The merchant seamen said they saw rocket propelled grenades being fired at them."
Hundreds of merchant ships travel this stretch of pirate-infested water. MacVicar is on the Winnipeg, one of a growing number of warships here to protect them.
The pirates move fast. To prevent a hijacking there is very little time for action. Within minutes three naval helicopters were in the air.
"The pirate skiff is breaking off," a crewman radioed. "They're heading north."
Suddenly, the pirates break off their pursuit of the Maria K and head for an American ship. It's the Maersk Virginia - sister ship to the Maersk Alabama, hijacked last month.
After U.S. Navy SEALs killed three of the Somali pirates holding the captain of the Maersk Alabama hostage, pirate leaders threatened retaliation. Maritime security sources said that greatly increased the risk to U.S. ships and crews sailing in these waters.
"Okay we're on the lookout for them now. we see 'em," the Winnipeg radioed. "Falco has just fired that warning shot."
Helicopters forced these pirates to turn back - foiled but still free to strike another day.