Thousands of Yemenis marched in the capital Sanaa on Sunday to protest a Saudi-led coalition airstrike a day earlier that hit a funeral hall packed with hundreds of mourners, killing over 140 people.

The casualty toll, given by a U.N. official, also mentioned over 525 wounded in what was one of the deadliest single attacks of the country's civil war. The rebel-controlled Health Ministry gave a lower figure, saying that 115 people were killed and over 600 wounded, many of them seriously.

Some of the demonstrators who marched outside the U.N. building in southern Sanaa blamed the organization for not ending the conflict and urged an independent investigation. Some protesters brandished automatic weapons and rebel supporters in the crowd called on people from the region to rise up and attack Saudi Arabia.

The Saudi military announced early Sunday it would launch an investigation into "reports about the regrettable and painful bombing" in Sanaa, without acknowledging that its coalition battling rebels in Yemen is the only force with air power in the conflict.

It is the latest in a string of bombings by the coalition that have struck hospitals, markets and other places where civilians congregate.

"The place has been turned into a lake of blood," said one rescuer, Murad Tawfiq.

Yemeni officials said the dead and wounded included military and security officials from the ranks of the Shiite rebels, known as Houthis, and their allies, loyalists of former President Ali Abdullah Saleh. The rebel alliance is battling the internationally-recognized government of President Abed Rabbo Mansour Hadi.

Saturday's funeral was held for Sheikh Ali al-Rawishan, the father of Galal al-Rawishan, the interior minister in the rebel-led government. Among those killed was Maj. Gen. Abdul-Qader Hilal, head of the capital's local council, officials said, while Galal al-Rawishan was seriously wounded.

In the aftermath of the strike, hundreds of body parts were found strewn in and outside the hall. Rescuers collected them in sacks. The strike left the building little more than a shell, with most of its walls and roof gone. Cars parked outside were mangled by the blast.

Mohammed Abdul-Salam, the Houthi spokesman in Sanaa, angrily denounced the airstrike as the latest act of "genocide" by the Saudi-led coalition.

"The silence of the United Nations and the international community is the munition of the murderers," he said. "Those murderers will not escape divine justice."

In a statement early Sunday, Saudi Arabia said an investigation would be launched into the strike. Previous investigations by the Saudis have blamed Houthi or rebel forces for gathering near the sites of their attacks.

"The coalition supporting the legitimate government in Yemen has announced that it is aware of reports about the regrettable and painful bombing of the Great Hall in Sanaa today, which led to the killing and injuring of casualties, as reported," the statement read.

It added: "The coalition confirms that its troops have clear instructions not to target populated area and to avoid civilians."

Jamie McGoldrick, the U.N. humanitarian coordinator in Yemen, said in a statement that the relief community in the country is "shocked and outraged" by the airstrikes. He condemned the "horrific attack" and reminded all parties to the conflict "that under international humanitarian law, they are obliged to protect civilians and civilian infrastructures." He called for an immediate investigation into the incident.

"The international community must exert pressure and influence on all parties to the conflict to ensure civilians are protected," McGoldrick said. "This violence against civilians in Yemen must stop immediately."

Initial reports from health officials in Sanaa indicate that over 140 people were killed and more than 525 injured, McGoldrick said.

U.N. Secretary-General Ban Ki-moon condemned the bombing in a statement Sunday, saying that "any deliberate attack against civilians is utterly unacceptable ... Those responsible for the attack must be brought to justice."

The strike also prompted outrage in Hadi's own government, with Foreign Minister Abdulmalik al-Mekhlafi taking to social media to condemn it as a "crime."

The incident has prompted the U.S. to initiate an immediate review of its already reduced support for the Saudi-led coalition, White House national security council spokesman Ned Price said. He warned that U.S. security cooperation with Saudi Arabia "is not a blank check."

The United States has backed the coalition with multi-billion dollar arms sales and provided logistical and intelligence support, though it reportedly began pulling some soldiers from that task in August over concerns about civilian casualties in Saudi-led airstrikes.

The Saudi-led coalition backs Hadi's government which, together with its own allies, is fighting the Houthis and Saleh loyalists in a civil war that broke out in 2014. It's a war largely overshadowed by the conflict against the Islamic State group elsewhere in the Middle East, though rights groups have mounted increased criticism of the Saudi-led airstrikes in recent months.

Saturday's attack comes after a Saudi-led coalition March 15 airstrike on a market in Yemen's northwestern city of Mastaba that killed at least 119 people. Saudi forces reportedly used U.S. munitions in that strike, which at the time was described as the second-deadliest of the Saudi campaign, after a July 2015 attack near a power plant in Mokha that killed at least 120 people.

A recent report by the U.N.'s human rights chief, Zeid Ra'ad al-Hussein, estimated that 3,799 civilians have been killed since the Saudi-led air campaign began in March of last year. The U.N. and rights groups estimate the conflict has claimed the lives of at least 9,000 people and displaced nearly 3 million more in the Arab world's poorest country.

According to the report, coalition airstrikes were responsible for 60 percent of civilian deaths over a yearlong span starting in July last year. Just under one-quarter -- 475 -- civilian deaths were attributed to rebel forces like those loyal to Saleh, and another 113 to affiliates of al-Qaida and the Islamic State group.