Paris-based Doctors Without Borders (MSF) tweeted that the Abs hospital in the rebel-held northwestern province of Hajja "was targeted by air strikes today at 15:45 Yemen time".
The Arab coalition has been battling Iran-backed rebels in Yemen since March 2015 in support of Yemen's government, after the insurgents seized Sanaa before expanding to other parts of the country.
Earlier this month, the coalition acknowledged "shortcomings" in two out of eight cases it has investigated of UN-condemned air strikes on civilian targets in Yemen.
Today it promised to probe another attack that MSF said killed 10 children this weekend at a school in the rebel-held northern province of Saada.
The strikes in Abs today killed six people and wounded 20, according to Ayman Mazkour, who heads the health sector in Hajja.
Residents in Abs said coalition jets, which have been striking rebel military targets in the town for days, hit the hospital and caused casualties.
Rebel sources said the coalition struck a first aid building adjacent to the facility.
Abs is adjacent to the town of Harad, on the border with Saudi Arabia, and from where rebels have repeatedly shelled areas on the kingdom's side of the frontier, causing both civilian and military deaths.
Harad itself is seeing fierce fighting and is frequently a target of heavy coalition air strikes.
Pro-government military sources, who are fighting alongside coalition forces in Harad, said that military vehicles had taken rebel casualties to the Abs hospital before today's air strikes on the facility.
London-based watchdog Amnesty International described the hospital's bombardment as "a deplorable act that has cost civilian lives, including medical staff."
"Today's air strike appears to be the latest in a string of unlawful attacks targeting hospitals highlighting an alarming pattern of disregard for civilian life," Amnesty's deputy director Magdalena Mughrabi said, demanding an investigation.
The raid comes less than 48 hours after MSF accused the coalition of killing 10 children in air strikes on a Koranic school in Saada on Saturday.
The coalition denied targeting a school, instead saying it bombed a camp at which rebels train underage soldiers.
United Nations chief Ban Ki-moon condemned the attack on today and called for a swift investigation.
Subscribe to Business Standard Premium
Exclusive Stories, Curated Newsletters, 26 years of Archives, E-paper, and more!