Libyan crisis: Latest developments

The source of the explosions was not immediately clear, but the gunfire appeared to signal a fourth night of U.S. and European air operations over Libya on Tuesday to enforce a no-fly zone.

There is, however, some controversy after reports that American rescue forces fired upon civilians while retrieving one of the crew members.

A high-ranking Navy officer tells CBS News Correspondent David Martin an investigation is underway into the reports. But during a briefing Tuesday, Admiral Samuel Locklear, refused to address the issue.

According to several eyewitness accounts, a plane strafed the field where the pilot went down. Villager Hamid Moussa el-Amrun said that he himself was shot, suffering shrapnel wounds in his leg and back, but still able to walk. He used an old broomstick as a crutch and said he held no grudge, believing it was an accident.

The reports of injuries were disputed, however.

CBS's Mandy Clark arrived at the scene and spoke to an eyewitness, who said there was some firing but absolutely no one was injured.

"He said he would understand why there might be firing if the Americans were on the ground," Clark told CBS Radio News.

"He certainly didn't think the shooting was against civilians , perhaps more of a warning firing to tell people to back off and stay away from the wreckage and to stay away from the pilot and the weapons officer," Clark said.

Another witness told Clark that the Americans fired on their own plane that was down, perhaps in an effort to destroy it so none of the weaponry or technology could be seized by other forces.

Witnesses told Clark that right after the plane crashed, there were flares shot by other planes, which can sometimes serve as a a warning for civilians to stay away from an area. These villagers were not aware of that.

U.S. F-15 fighter jet down in Libya, crew "safe"

U.S. Navy Adm. Samuel J. Locklear told Pentagon reporters Tuesday that the coalition is "considering all options" in light of the attacks, but he did not elaborate.

Misrata is one of the cities that President Barack Obama has demanded that forces of leader Moammar Gadhafi retreat from.

In a Dec. 20, 2007, interview with The Boston Globe, Obama was asked about the president's constitutional authority to bomb Iran without seeking authorization from Congress.

"The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation," Obama said four years ago. "As commander in chief, the president does have a duty to protect and defend the United States. In instances of self-defense, the president would be within his constitutional authority to act before advising Congress or seeking its consent."

In a letter to Congress on Monday, Obama said he authorized the involvement of the U.S. military as part of a "multilateral response authorized under U.N. Security Council Resolution 1973."

"I have directed these actions, which are in the national security and foreign policy interests of the United States, pursuant to my constitutional authority to conduct U.S. foreign relations and as Commander in Chief and Chief Executive," he said.

Under the congressional War Powers Resolution, the president has the authority to launch U.S. actions for 60-90 days before seeking authorization from Congress. However, presidents have not always sought congressional approval, creating tensions between the two branches of government over the authority.

U.N. Secretary-General Ban Ki-moon says that "until he stops, I think that this military operation to enforce a no-fly zone will have to continue."

Ban spoke during a visit Tuesday with post-revolutionary leaders in Tunisia, Libya's neighbor.

Ban said that the military operation by an international coalition is neither interference in Libya's internal affairs nor "occupation by foreign forces." It is "simply protecting the civilian population."

He added that "the first and foremost thing should come from Col. Gadhafi. He must stop killing his own people."

Francois Fillon says France's role in the multinational effort aimed at stopping attacks against Libyan civilians "can have domestic repercussions," and that French intelligence services have been mobilized.

Fillon said Tuesday "threats were made" against France, but did not elaborate. He spoke at the start of a parliamentary debate over the country's role in Libya.

France along with the United States, Britain and other European countries - with backing from Arab countries - has been leading the charge with air strikes and missile attacks against Qaddafi's forces since Saturday.

"I hope that Col. Qaddafi will soon come to the realization that murdering his own people is not a solution and that it is time for him to step aside," said Powell, who was senior military assistant to Secretary of Defense Caspar Weinberger during U.S. airstrikes on Libya in 1986.

Powell later served in many roles that involved assessing Qaddafi's regime, including as chairman of the Joint Chiefs of Staff and Secretary of State.

He said the new governments on either side of Libya - Tunisia and Egypt - could serve as models for the region on bringing about democratic change, "if it is done properly."

"The most powerful force at work today in the world is economic development and creation of wealth," said Powell, speaking at a regional security conference. "It is economic development and wealth creation that will lift people out of poverty, provide an education to young people, and create jobs for people."

Powell predicted only governments "wise enough to reform themselves" can easily ride out the wave of change in the Arab world, but he gave no specific examples.

Fox News correspondent Jennifer Griffin reported Monday that the British military had to call off an attack on the Libyan ruler's compound because journalists had been taken there on a trip to view earlier bomb damage. She says Fox correspondent Steve Harrigan avoided the government-sponsored trip because of concern about being used as a shield.

An angry Robertson took to the air on CNN and called the allegation "outrageous and absolutely hypocritical." He says Fox sent a security guard with a camera on the same trip.

Griffin apologized for not noting the Fox presence, but stood by the human shields charge.

"One need only consider the mosque in western Tripoli," he said. "This area was in a place where heavy fighting took place earlier this month. The mosque was raised to the ground. This is a sign of how far Col. Qaddafi is willing to go."

Another GRAPHIC Youtube video dated March 20 claims to show victims of Qaddafi forces' attack on Misrata.

A senior defense official said Monday the attacks thus far had reduced Libya's air defense capabilities by more than 50 percent.

Rate of attacks on Libya air defenses slows
Complete coverage: Anger in the Arab World

McCain, R-Ariz., said on CBS' "The Early Show" that he hopes the United States, or others in the international community, supplies rebels with arms, as it once did insurgents fighting the Russian occupation of Afghanistan.

McCain: I hope U.S. arms Libyan rebels

Rebels, Qaddafi forces face standoff on ground