The government voiced support for the anti-Houthi campaign in a statement, following a closed meeting chaired by President Abdu-Rabbu Mansour Hadi and attended by senior officials in Saudi Arabia's capital Riyadh.

Hadi hailed what he described as the "popular uprising" against the Houthi rebels in Sanaa as a "historic moment" to bring back legitimacy to Yemen.

The Yemeni president also extended his hand to the forces loyal to former President Ali Abdullah Saleh and called for "opening a new page with all the political parties in the country and forgetting what happened in the past."

Hadi's Aden-based government also called for "unity and demanded the political parties in Yemen to form a national alliance that overcomes the differences of the past and move on to confront the Iranian-backed Houthi militias."

Earlier in the day, more than 80 people were killed and 120 others injured during fierce armed confrontations between the elite Republican Guard Forces loyal to Saleh and the Houthis in different areas of Sanaa.

The Houthis and Saleh used to be allies during the three-year military conflict with the Saudi-backed government and the newly-recruited forces of Hadi across Yemen.

On Saturday, Saleh delivered a televised speech calling upon Yemenis to rise up and fight against the Houthis.

"I call upon all Yemenis to come together and do their national duty by defending our republic, institutions and freedom against the aggression of the Houthi militias which lasted for three years now," Saleh said.

Saleh also announced his willingness to conduct negotiations with the Saudi-led coalition via the Parliament.

"I also urge the coalition to conduct a ceasefire in Yemen, open airports, allow humanitarian aid into the devastated country. Our hand is extended to them to start a new chapter of relations," he added.

Security sources in Sanaa told Xinhua that intense street gun fights took place between pro-Saleh forces and the Houthi militants using different types of heavy and medium weapons.

Saleh's forces managed to retake the Sanaa International Airport, the 48th military camp, the Presidential Compound, key government institutions and ministries after fierce clashes with Houthi militias.

Sources close to Saleh said that "the popular uprising and the military campaign against Houthis will continue in Sanaa and some neighboring provinces on all different levels."

The sources also said that "Qatar tried to organize desperate mediation to end the clashes in Sanaa. The Qataris attempted to convince Saleh to withdraw his forces from areas under control in Sanaa and negotiate with Houthis to reach a settlement, but he strongly refused and the mediation failed."

On the other hand, the Saudi state media reported that Saleh loyalists freed his rival Hadi's Defense Minister Major General Mahmoud al-Subaihi from a Houthi prison in Sanaa. He was captured by Houthi forces in southern Yemen in mid 2015.

Chief of Houthi Abdul-Malik Al-Houthi gave a speech on Saturday evening saying that "all residents of Sanaa enjoyed peace. But unfortunately, those militants supported by Saleh are seeking to undermine it and spread chaos."

The Houthi leader called for peace and stability and demanded the tribal leaders and others to intervene to stop this sedition and end the escalation of situation in Sanaa as soon as possible.

Military commander loyal to the Houthi group said that the fight for taking full control over Sanaa will continue overnight and claimed they will take back all the neighborhoods in Sanaa within 24 hours.

After the fiery speeches of the two warring rival leaders, Sanaa witnessed a cautious calm that prevailed in the city's neighborhoods despite the sporadic gunfire and explosions that rocked the city in the past hours.

Thousands of terrified citizens and children are trapped in the middle of Sanaa, and each side mobilizes fighters and arms into the diplomatic district in preparation for possible violent confrontations tonight, according to local residents.

The Republican Guard Forces loyal to Saleh announced a curfew, asking people to remain indoor starting from 10:00 p.m. Sanaa time.

In September 2014, the two factions unified and toppled the legitimate government of Hadi and forced him along with his cabinet members into exile in neighboring Saudi Arabia.

The fragile alliance between the two parties has faced much trouble over the vying of power.

On Aug. 26, a deadly fighting erupted near the residential house of Saleh's son in the southern part of Sanaa, during which the Houthis killed a senior security official close to Saleh.

Houthis and Saleh's party have since been trading accusations of secret links with the U.S.-backed Saudi-led military coalition.

The coalition intervened in the Yemeni conflict in March 2015 to roll back the Iranian-allied Houthi group and reinstate Hadi into power.