ABIDJAN, Ivory Coast — At least six women were shot dead here on Thursday as they protested against the continued rule of Laurent Gbagbo, witnesses said.

The women were taking part in one of a number of all-women marches that have sprung up here over the past week in response to Mr. Gbagbo's refusal to cede power after losing a presidential election last year. Previously, these marches have been dispersed by troops firing in the air.

But on Thursday, Mr. Gbagbo's forces responded to the demonstration in the tense Abobo neighborhood by shooting into the marching crowd of hundreds of women, two witnesses said. Six were killed instantly in the machine-gun fire, others were wounded, and the march dispersed in a panic, according to the witnesses. Amateur video taken on the spot appeared to confirm their account.

The shootings of the women underscored the continued escalation of the violence that has gripped this sprawling West African port of some four million people in the wake of Mr. Gbagbo's armed campaign to stay in office after the election more than three months ago.

Gun battles last week in Abobo killed 26 people, according to the United Nations, which said Thursday that 200,000 people had fled the violence in the dusty, mud-brick neighborhood north of the center here. Abobo largely supports the man the United Nations, the African Union and most foreign powers say defeated Mr. Gbagbo, Alassane Ouattara.

Mr. Gbagbo's security forces regularly come into pro-Ouattara neighborhoods, often at night or early in the morning, firing machine guns, rifles or grenade launchers into the air or into buildings. Residents of these neighborhoods speak of terror and sleepless nights at these "muscular descents," as they are often called.

Last week, there was a riposte in Abobo by what residents and the United Nations call "the invisible commando," and some of Mr. Gbagbo's forces were killed.

It is unclear what connections, if any, the "invisible commando" has with the Ouattara camp. At least one independent newspaper here has published statements purporting to come from the shadowy forces, denying such ties.

Mr. Gbagbo's forces arrived soon after the women's march started Thursday morning, in a convoy of military vehicles that appeared to be heading for the northern exurb of Anyama.

"The forward tank started firing," said one Abobo resident, Idrissa Diarrassouba. "Right away six women were killed. I was right there, beside them. They just fell."

On a video provided by Mr. Diarrassouba, gunshots can be heard, and the bloodied bodies of at least four women lying face down on the ground are seen. Near them, also on the ground, are the leafy branches that women in protests here hold aloft as they chant, "We want peace."

Another witness in Abobo spoke of a sudden "burst" of machine-gun fire.

"The women tried to march," said the witness, Idrissa Sissoko. "They are against Gbagbo staying in power."

When the vehicles of Mr. Gbagbo's forces arrived, the women "were scared," Mr. Sissoko said.

"I said, 'They won't fire.' Then, there was a burst of machine-fun fire," he said.

He also spoke of seeing six women being shot. "I saw six bodies lying there, suddenly" he said.

"It was a peaceful march by women," Mr. Sissoko added. "It was just women."

A spokesman for Mr. Gbagbo's government could not immediately be reached for comment.

On Thursday, the members of the United Nations Security Council issued a statement saying they were "deeply concerned about the recent escalation of violence" after "the reported attacks on civilians, including women."

A State Department spokesman, Philip J. Crowley, also denounced the shootings. "The moral bankruptcy of Laurent Gbagbo is evident as his security forces killed women protesters and his country runs out of resources," Mr. Crowley said on Twitter.

After the shootings Thursday morning, members of pro-Gbagbo youth militias blocked access to the Abobo neighborhood.

The United Nations office here noted what it said was a "new phenomenon" of victims being burned alive in the violent confrontations between the partisans of Mr. Gbagbo and those of Mr. Ouattara. It said at least three had suffered this treatment, without noting which side they were on. It also said the "invisible commando" was preventing some families from leaving the combat zones, notably Abobo, forcing them to live without water or electricity in places like churches.

Adding to the country's human crisis, the United Nations noted, is the fact that large areas of Ivory Coast — those supporting Mr. Ouattara principally, in the north, center and west — have been deprived of electricity and water, since Feb. 28. Earlier this year Mr. Gbagbo took over the country's electricity company.

In Abobo, small arms fire has given way to the use of heavy weaponry, the United Nations said.

"Today, in Abobo, we are despondent," Mr. Sissoko said. "We don't know what to do. We are tired. And we don't sleep at night."