(CNN) -- Shiite Houthi rebels overtook the presidential palace in Yemen's capital, Sanaa, on Tuesday, marking what a government minister called "the completion of a coup."
"The President has no control," Minister of Information Nadia Sakkaf told CNN as clashes raged.
President Abdu Rabu Mansour Hadi was thought to be in his private residence at the time -- not in the palace. There were reports of clashes near the residence.
And the Prime Minister's residence was under attack from the street, Sakkaf said.
The regime still controlled the city of Aden, and it closed the port of Aden as well as roads leading into and out of Sanaa, according to Yemeni state TV, controlled by the government.
Power vacuum could benefit terrorist group AQAP
The global stakes are high. Yemen is home to al Qaeda in the Arabian Peninsula, or AQAP, the terror network linked to such attacks as the recent slaughter at French satirical publication Charlie Hebdo. AQAP also tried to blow up a plane landing in Detroit in 2009.
The battle against AQAP has helped make Yemen's government a U.S. ally in the fight against al Qaeda. A power vacuum often benefits terrorist groups.
The Yemeni government has been grappling with pressure not only from the Sunni Muslim AQAP but also from Houthi militants, Shiite Muslims who have long felt marginalized in the majority Sunni country.
Houthi leader: Conspiracy links Yemen to Charlie Hebdo attack
"We are the victims of corruption and false promises," Houthi rebel leader Abdul Malik al-Houthi said in a televised address on a network controlled by Houthis and based in Beirut, Lebanon. "The government did not respect the peace and partnership deal from September. We are trying to bring some legitimacy to the government."
He complained of economic struggles and poverty.
Al-Houthi also said there is an international conspiracy to link Yemen to the attacks in Paris.
"Yemeni people have two options -- to move against the foreign agendas, or stand against them firmly since they seek to spread chaos in Yemen. This is why we moved with the Yemeni people though many powers inside and outside Yemen are angered. But the Yemeni people are with us and understand our goals," he said.
AQAP claimed responsibility for the Charlie Hebdo attack, and U.S. investigators have worked on the assumption that attacker Said Kouachi met the late American terrorist cleric Anwar al-Awlaki at some point in Yemen and received orders from AQAP, a U.S. official told CNN.
Tuesday's developments came a day after heavy fighting between government forces and Houthis left nine people dead and 67 others injured, Yemen's Health Ministry said, before the sides agreed to a ceasefire.
Gunfire could be heard sporadically across Sanaa on Tuesday.
U.S. Embassy vehicle comes under fire
Unknown assailants fired shots Monday night at a U.S. Embassy vehicle in Sanaa, the U.S. Embassy said Tuesday.
The shooters fired first into the air and then turned the guns on the vehicle, the embassy said. The vehicle carried U.S. diplomatic personnel and was at a checkpoint near the embassy at the time. No injuries were reported.
The embassy is known to use SUVs that are recognizable as U.S. government vehicles.
Two U.S. Navy warships moved into new positions in the Red Sea late Monday to be ready to evacuate Americans from the embassy if needed, a U.S. official with direct knowledge of the planning told CNN.
U.N. Secretary-General Ban Ki-moon, in a statement, called on "all sides to immediately cease all hostilities, exercise maximum restraint, and take the necessary steps to restore full authority to the legitimate government institutions."
Mark Lyall Grant, UK ambassador to the United Nations, said the U.N. special adviser on Yemen, Jamal Benomar, was on his way to Sanaa and would brief the U.N. Security Council from there.
"There's a lot of conflicting reports, but clearly the situation has deteriorated very significantly over the last 48 hours, and that's why the Security Council needs to meet and decide its response," the UK envoy said.
Houthis swept into the capital last year, sparking battles that left more than 300 dead in a month. In September, they signed a ceasefire deal with the government, and Houthis have since installed themselves in key positions in the government and financial institutions.
But tensions flared again last weekend as Houthis said they abducted presidential Chief of Staff Ahmed bin Mubarak in Sanaa on Saturday. Osama Sari, senior media adviser to the Houthi movement in Yemen, said Houthis detained bin Mubarak because the President wanted to introduce a new constitution without the Houthis' approval.