Protesters described coming under a hail of bullets as they tried to march from several districts around the city toward Tripoli's central Green Square. One man among a crowd of thousands said gunmen on rooftops and in the streets opened fire with automatic weapons and even an anti-aircraft gun.
"In the first wave of fire, seven people within 10 meters (yards) of me were killed. Many people were shot in the head," the man, who was marching from Tripoli's eastern Tajoura district, told The Associated Press. "It was really like we are dogs."
"We can't see where it is coming from," another protester from Tajoura said of the gunfire. "They don't want to stop." He said a man next to him was shot in the neck.
Militiamen opened fire on other marches in the nearby Souq al-Jomaa and Fashloum districts, where witnesses reported four killed. The reports could not be immediately confirmed.
In the evening, Gadhafi appeared before a crowd over more than 1,000 supporters massed in Green Square and called on them to fight back against protesters and "defend the nation."
"Retaliate against them, retaliate against them," Gadhafi said, speaking by microphone from the ramparts of the Red Castle, a Crusader fort overlooking the square. Wearing a fur cap and sunglasses, he shook his fist in the air, telling the crowd, "Dance, sing and prepare. Prepare to defend Libya, to defend the oil, dignity and independence."
He warned, "At the suitable time we will open the arms depot so all Libyans and tribes become armed, so that Libya becomes red with fire." The crowd waved pictures of the leader and green flags as he said, "I am in the middle of the people in the Green Square. ... This is the people that loves Moammar Gadhafi. If the people of Libya and the Arabs and Africans don't love Moammar Gadhafi then Moammar Gadhafi does not deserve to live."
Friday's marches were the first significant protests by regime opponents in the capital since early this week, when militiamen launched a bloody crackdown on protesters that left dozens dead. In the morning and night before, SMS messages were sent around urging, "Let us make this Friday the Friday of liberation," residents said. The residents and witnesses all spoke on condition of anonymity for fear of retaliation.
Tripoli, home to about a third of Libya's population of 6 million, is the center of the eroding territory that Gadhafi still controls. The uprising that began Feb. 15 has swept over nearly the entire eastern half of the country, breaking cities there out of his regime's hold.
Even in the pocket of northwestern Libya around Tripoli, several cities have also fallen into the hands of the rebellion. Militiamen and pro-Gadhafi troops were repelled Thursday when they launched attacks trying to take back opposition-held territory in Zawiya and Misrata, near the capital, in fighting that killed at least 30 people.