Misrata, Libya (CNN) -- A NATO airstrike Wednesday on the seaside town of Misrata killed 11 rebel fighters and wounded two others, witnesses told a reporter, who saw the bodies.

Angry survivors told Marie Colvin of The Sunday Times that they and the victims were on the coast, east of a steel plant, when a NATO plane bombed them. There were no other planes in the sky, the survivors said.

NATO spokesman Eric Povel said he knew nothing about the report and would likely not learn more for several hours.

The incident occurred on a day in which pro-government forces launched the heaviest shelling yet on the port of Misrata, much of which appeared to be a wasteland, rebels said.

"I'm looking around, I can't find a single building that's not either damaged or destroyed," CNN's Reza Sayah said from Tripoli Street, the city's major thoroughfare.

From the time NATO began its operation on March 31 until Tuesday, the organization had conducted 3,981 sorties, of which 1,658 were strike sorties, according to an update issued Wednesday.

Ships chartered by the International Committee of the Red Cross and the International Organization for Migration (IOM) departed port Wednesday, carrying people intent on fleeing the violence.

The ICRC-chartered ship evacuated more than 600 civilians from the city, it said.

The IOM-chartered ship was carrying about 935 migrants and Libyans en route to Benghazi, the organization said in a news release.

Also aboard was a group of journalists, including a French journalist who was in intensive care after being shot in the neck, it said.

In Washington, President Barack Obama on Wednesday authorized up to $25 million in nonlethal commodities and services to be made available to "support key U.S. government partners such as the Transitional National Council in efforts to protect civilians and civilian-populated areas under threat of attack in Libya."

The United States considers the Libyan opposition group the Transitional National Council worthy of U.S. support, but has not formally recognized the group, Ambassador to Libya Gene Cretz said Wednesday. But Cretz said the lack of formal recognition has not stopped the United States from aiding and supporting the opposition.

A three-member panel arrived in Libya on Wednesday to begin a U.N.-ordered inquiry into reports of violence and human rights abuses. The team, led by Professor Cherif Bassiouni, an Egyptian jurist and war crimes expert, was sent by the Human Rights Council. Last month, the U.N. General Assembly suspended Libya's membership in the Human Rights Council.

The U.N. Office for the Coordination of Humanitarian Affairs said Wednesday it has established an international aid presence in Tripoli, with humanitarian workers also in Benghazi and the neighboring countries of Tunisia, Egypt, Chad and Niger. Aid agencies are seeking about $310 million for relief operations and have received $129 million, the U.N. office said.

Also Wednesday, government officials took reporters to the city of Tarhuna, south of Tripoli, where they said civilians were volunteering to be trained to defend Libyan leader Moammar Gadhafi from NATO. At a training camp there, reporters observed civilians learning basic military skills. Some of the volunteers appeared to be as young as 15 years old, the reporters said.

NATO is leading an international military operation in Libya that includes airstrikes targeting Gadhafi's military resources. It is operating under a U.N. Security Council resolution authorizing any means necessary -- with the exception of foreign occupation -- to protect civilians.

Witnesses said three people were killed and several were wounded after government shells detonated Tuesday near a refugee camp in the critical port area. Thousands of migrants have been housed there as they wait for ships to carry them to safety.

Opposition forces said they believe that, had NATO forces not intervened with air attacks Tuesday night, the shelling would have continued.

NATO said six military vehicles, seven technical vehicles and a surface-to-air missile launcher were targeted on Tuesday in the vicinity of Misrata.

Though Gadhafi's regime said last week that it was going to suspend operations in Misrata and let tribes deal with the rebels, heavy shelling suggests pro-government forces aren't done with the city.

As many as 1,500 migrants are believed to remain in Misrata in need of evacuation, IOM said. In recent weeks, nearly 626,000 people have abandoned Libya for Tunisia, Egypt, Niger, Algeria, Chad and Sudan, it said.

Some 615,000 people, including large numbers of third-country nationals, have fled Libya, more than 10,000 from Misrata.

Misrata, the third-largest city in the North African country, has been hemmed in on three sides by Gadhafi's forces. Though rebels said they had gained control of the city's center and had pushed government forces outside the city, they said Gadhafi's forces were continuing to attack Misrata with heavy weaponry.

The port has served as a crucial route of escape and as a lifeline to humanitarian aid.

CNN's Frederik Pleitgen, Elise Labott, Raja Razek, Saad Abedine and Joe Sterling contributed to this report.