(CNN) -- Multinational naval forces rescued the crew of a Chinese merchant ship from pirates in the Gulf of Aden on Wednesday, shipping sources said.
A French warship keeps guard over commercial vessels in the Gulf of Aden last month.
About 30 crew members aboard the Zhenhua 4, a heavy lift ship registered in St. Vincent and the Grenadines, barricaded themselves in the ship's accommodation room as nine pirates boarded the vessel, according to Andrew Mwangura of the Kenyan Seafarers Association.
The crew radioed for help, and a coalition warship and two helicopters responded, firing on the pirates and forcing them from the ship about five hours after they boarded, Mwangura said.
Pirates hijacked three vessels Tuesday, Mwangura said, including the Malaysian tug Masindra 7, the Turkish cargo ship Bosphorus Prodigy, with a crew of 11 aboard, and a private yacht.
With the latest seizures, the gunmen are holding 18 vessels.
More than 124 incidences -- attempted and averted attacks and successful hijackings -- have been recorded up to this point in 2008, according to Mwangura.
A multinational naval force, including vessels from the United States, NATO member states, Russia and India, has been patrolling the Indian Ocean waters near the Gulf of Aden, which connects the Red and Arabian seas, following a sharp increase in pirate attacks in the region.
Around 20,000 oil tankers, freighters and merchant vessels pass along the crucial shipping route each year.
On Tuesday, the U.N. Security Council passed a resolution allowing military forces to chase pirates onto land in cases of "hot pursuit."
The resolution, which passed unanimously, expands upon existing counter-piracy tools.
U.S. Secretary of State Condoleezza Rice was at the United Nations on Tuesday for a discussion of the piracy problem and for the Security Council vote. Watch how the United States hopes to fight piracy »
"I wouldn't be here seeking authorization to go ashore if the U.S. government -- perhaps most importantly the president of the United States -- were not behind this resolution," Rice said after the council vote.
Asked if she thought U.S. troops soon would be on land chasing pirates, Rice would not speculate.
"The United States is part of an international effort," she said. "We do have naval forces that have been involved in this effort. What this [resolution] does is to authorize that the boundary of the maritime cannot become a safe-haven boundary for pirates. What we do -- or do not do -- in issues like hot pursuit, we'll have to see ... case by case."
Earlier, in remarks to the Security Council, Rice described the growing problem of piracy as "a symptom of the instability, the poverty, the lawlessness that have plagued Somalia for the past two decades," adding that the Bush administration "does believe that the time has come for the United Nations to consider and authorize a peacekeeping operation."
Meanwhile, Chinese Vice Foreign Minister He Yafei said Tuesday that Chinese warships may join international anti-piracy efforts.
"China is seriously considering sending naval ships to the Gulf of Aden and waters off the Somali coast for escorting operations in the near future," China's official Xinhua news agency quoted He as saying.