Houthi group claimed it was a Saudi-led strike on a school.
At least 10 children were killed and 21 injured in northern Yemen on Saturday, aid group Medecins Sans Frontieres said, as the country's parliament convened for the first time in almost two years.
The country's dominant Houthi group claimed it was a Saudi-led air strike on a school. A spokesman for the Saudi-led coalition had no comment on the attack.
Saudi Arabia and its allies have launched thousands of air strikes against the Houthi rebels since they drove the internationally recognised government into exile in March 2015.
"@MSF received today 21 injured & 10 deaths in Haydan #Saada. All were under 15 years old," Medecins Sans Frontieres, the aid group said on its official Twitter account.
Mohammed Abdul-Salam, a senior official from the Houthi movement whose main support base is in Saada, blamed the attack on the mostly Gulf Arab military coalition that has been at war with the group for over a year.
At least 6,400 people have been killed in the conflict, around half of them civilians.
The armed Houthis and their allies in the General People's Congress (GPC) party headed by powerful ex-president Ali Abdullah Saleh control the capital Sanaa and have so far withstood the coalition campaign.
'Illegal' parliament convened
The session in rebel-held Sanaa was the first in almost two years, and comes after the Houthis rejected a UN peace plan and appointed a council to run the country.
President Abd-Rabbu Mansour Hadi and his internationally recognised government has denounced the parliamentary session as a "violation" of the constitution and a "crime punishable by law", in remarks carried by the official sabanew.net website.
"Whatever takes place at this meeting has no legal effects and cannot be implemented," he said.
Parliamentary sources said 91 lawmakers in the 301-member national assembly attended, and all voted in favour of the council created last week. According to the constitution, more than 150 lawmakers must be present for a vote to be held.
UN envoy Ismail Ould Cheikh Ahmed has described the rebel governing council as a violation of commitments to the peace process.
Sanaa airport remains shut
Arab coalition air strikes have hit rebel positions across northern Yemen as well in as the southwestern province of Taez as ground fighting raged .
Houthi spokesman Mohammed Abdulsalam wrote on Facebook that Sanaa airport would remain shut for at least three more days after being closed since Tuesday.
In Saudi Arabia, the civil defence agency announced that five foreign residents were wounded in shelling from Yemen Saturday in the Jazan border region, without giving their nationalities.
The Houthi rebels overran Sanaa in September 2014 and then fought their way into other parts of Yemen, forcing Hadi and his government into exile in Saudi Arabia.
A Saudi-led coalition has been fighting the Houthis and their allies -- supporters of ousted president Ali Abdullah Saleh -- since March last year to shore up the Hadi government.
After U.N.-backed peace talks to end the war collapsed last week, the Houthis and the GPC set up a governing council to rule the country despite U.N. and government opposition.
The assembly convened within earshot of bombings by Saudi-led warplanes on military bases several miles away.