Houthi rebels have taken over the presidential palace in Sanaa, Yemen, after several hours of clashes with government security forces. The fighting between security forces and rebels forced thousands of people in the city to clear the streets and to stock up on food supplies. Humanitarian groups in the area said they were preparing to serve an increased number of people if the violence in the capital continues.

It is not clear if President Abed Rabbo Mansour Hadi escaped the palace before the rebels stormed the building. The BBC reported that Hadi was still in the building but that he was safe. Others reported on social media that the president had escaped. The United Nations Security Council has called an emergency meeting. Ban Ki-moon condemned the outbreak of violence and called for an immediate restoration of order.

“The Secretary-General is gravely concerned about the deteriorating situation in Yemen,” a statement read. “He deplores the heavy fighting between Ansarallah (Houthi) armed groups and Yemeni presidential guards throughout Sanaa.”

It is not yet clear if the Houthi rebels will demand control of the government or if they will negotiate with the U.N. and other Yemen government officials. The Houthi rebels have significant support in the capital but lack support outside Sanaa.

Abdul-Malik al-Houthi, the 33-year-old leader of the Houthi rebels, aired a video message after the takeover of the palace and blamed President Hadi for the chaos in the capital. Also in his video message, al-Houthi said that he would not negotiate if there were any measures implemented by the international community on his group.

"I advise the U.N. Security Council ... (that) you will not benefit from any measures you wish to take" against the Houthis, he said, the Associated Press reported. "We are ready to face the consequences, regardless of what they are."

The events Tuesday came a day after some of the most violent fighting in Sanaa since 2011. The Houthi rebels battled the army near the presidential palace and surrounding the prime minister's home.

The seize of the presidential palace on Tuesday was the last attempt by the Houthi rebels to take over the capital completely. Tensions have been running high in perpetually unstable Yemen ever since Houthi supporters protested in the streets this summer, calling for more opportunities and representation in the Yemeni government.

The Houthis officially captured Sanaa on Sept. 21, 2014. Following the takeover, the Houthis signed a power-sharing deal with the government, angering Sunnis. The violence in the capital intensified after Houthis protested the nomination of a new prime minister by Hadi. Houthi leaders said they were not consulted and did not agree to the choice. 

After more than a month of clashes and political infighting, the Houthi rebels showed in October that they were willing to negotiate Yemen's future with President Hadi. Rebel leaders gave Hadi 10 days to form a new government. If the president refused, the rebels said, they would present the country with an alternative government of their own choosing. The United Nations special envoy to Yemen, Jamal Benomar, has been holding negotiations with the two groups ever since.