Forces loyal to the president-elect of the Ivory Coast on Wednesday attacked the residence of embattled strongman Laurent Gbagbo, who was clinging precariously to power a day after his military commanders offered to surrender, news agencies reported.

Witnesses and aides to President-elect Alassane Ouattara told Reuters and the Associated Press that pro-Outtara forces had entered the gates of Gbagbo’s residence, where Gbagbo was reportedly holed up in an underground bunker.

“At the current moment they have not yet captured Gbagbo but it will happen soon,” Outtara spokeswoman Affoussy Bamba told AP. “They opened the gates and noted that the residence is surrounded by heavy weaponry. . .Now the objective is to capture him.”

Although military strikes earlier this week by France and the United Nations weakened Gbagbo’s hold on power, French and U.N. officials said they were not part of the attacks on the residence Wednesday.

On Tuesday, French Foreign Minister Alain Juppe and other officials insisted that Gbagbo was on “the brink” of yielding power, according to the Reuters news agency. But Gbagbo was defiant, telling a French television station, LCI, in a telephone interview from his residence, “I won the election, and I am not negotiating my departure,” according to the Associated Press.

The events in the commercial capital of Abidjan marked the end of a four-month standoff between Gbagbo’s forces and the United Nations, which led international efforts to persuade him to step down.

They also represented an extraordinary military initiative by France and the United Nations to help dislodge an entrenched African leader who has ruled the once prosperous, cocoa-producing country since 2000.

The United Nations and France portrayed their role in Ivory Coast as a limited military operation aimed at protecting civilians and preventing sniper fire and mortar attacks against U.N. personnel. During the past week, Gbagbo’s forces have injured 11 U.N. peacekeepers, including four who were seriously injured by a rocket-propelled grenade attack against a U.N. armored personnel carrier.

But a series of French and U.N. helicopter gunship attacks against Gbagbo’s military bases and other vital installations softened Gbagbo’s last lines of defense, paving the ground for a final military offensive by forces loyal to Ouattara, the Ivory Coast’s internationally recognized president-elect.

“The military battle is over,” Youssoufou Bamba, Ouattara’s U.N. envoy, said Tuesday. Gbagbo’s forces “have no ammunition, and they are surrendering. I understand they are now negotiating the terms of the surrender” with the French government. “For our part, we want Gbagbo’s military to surrender without conditions.”

Even Gbagbo’s backers acknowledged that his days were numbered. Zakaria Fellah, a foreign policy adviser to Gbagbo, said he believed Gbagbo’s most fervent supporters would continue fighting but conceded that “mathematically, the game is over.”

Fellah, who said he spoke Tuesday morning to Gbagbo’s wife, Simone, insisted that Gbagbo would not surrender from the bunker at his house where he took shelter. He “is not negotiating anything. This is a fight to the end for him, his wife and what you guys call his hard-line supporters,” Fellah said. “She said, and I’m quoting, ‘It would be a beautiful end.’ I don’t know what it means, but I think they are ready to die.”

The crisis in Ivory Coast comes more than four months after Gbagbo was defeated by Ouattara in a U.N.-sanction election in November. Gbagbo refused to accept the results of the election, which he claimed was tainted by fraud, and unleashed a campaign of violence against suspected supporters of Ouattara and the U.N.’s 9,000-strong peacekeeping mission. The post-election violence has displaced as many as 1 million Ivorians.

Months of high-level diplomatic efforts, led by African governments and backed by Western financial sanctions, failed to force Gbagbo from power. But last month, a coalition of former rebels, police officers and soldiers launched a military offensive, beginning in rebel territory in the north, that easily overwhelmed Gbagbo’s forces, capturing town after town before entering Abidjan last week, where the warring parties reached a stalemate.

The United Nations and France, which seized Ivory Coast’s main airport Sunday, turned the tide of battle, launching helicopter gunship attacks to neutralize Gbagbo’s heavy weapons.

On Tuesday, Gbagbo’s top security officials — Gen. Philippe Mangou, head of the Ivorian army; Gen. Thiape Kassarate Edouard, commander of the national police; and Gen. Bruno Dogbo Ble, head of the Republican Guard — informed the United Nations that they would cease fighting and surrender their weapons.

President Obama, who has largely deferred to France in Ivory Coast, said Tuesday that he strongly supported the military operation against Gbagbo’s forces. “Tragically, the violence that we are seeing could have been averted had Laurent Gbagbo respected the results of last year’s presidential election,” Obama said. “To end this violence and prevent more bloodshed, former president Gbagbo must stand down immediately, and direct those who are fighting on his behalf to lay down their arms.”

Obama also touched on reports by U.N. officials and human rights advocates that Ouattara’s forces committed abuses during their military offensive, killing hundreds of people in the western town of Duekoue. Obama urged both sides in the conflict to exercise restraint, saying he was concerned “about reports of massacres in the western region of the country, and the dangers faced by innocent civilians.”

The United Nations and Human Rights Watch have cited evidence that Ouattara’s forces have carried out reprisal killings against suspected Gbagbo supporters and summarily executed prisoners.

“President Ouattara should signal the end of a long era of impunity, in which thousands of Ivorian victims of horrendous crimes have been denied justice,” said Philippe Bolopion, U.N. director for Human Rights Watch.