At least seven people died and more remain trapped under rubble after "bunker-buster" bombs destroyed the M10 hospital in Aleppo on Monday, opposition activists from the Aleppo Media Center said.
Monday's attack marked the third time in a week the M10 hospital was bombed. Airstrikes also pummeled the hospital, in rebel-held eastern Aleppo, last Wednesday and Saturday.
The seven people killed Monday include two medical staff members and five maintenance workers who were trying to repair the hospital after the previous airstrikes, activists and hospital staff said.
While part of hospital was above ground, most of its operations -- including the intensive care unit and emergency rooms -- were kept underground as bombings remain a constant threat in Aleppo.
Just hours earlier, an international aid organization said an underground hospital in Hama province was also hit by a suspected "bunker-buster" bombs.
That hospital was hit Sunday, said the Union of Medical Care and Relief Organizations (UOSSM). The opposition Syrian Observatory for Human Rights said the hospital was in the rebel-held area of Kafr Zita.
"It is suspected that the hospital was targeted by so-called 'bunker-buster' missiles, as it was well fortified in a cave and impervious to previous attacks," said Dr. Abdallah, the hospital's director and head of Hama's healthcare directorate, according to UOSSM.
The hospital performed 150 operations and treated up to 50 intensive-care cases a month. It was thought to be well-protected from potential attacks due to its location.
No one was killed in the attack near Hama, but it destroyed the hospital's emergency department, forcing all patients and medical equipment to be moved.
The Hama region is under the control of Syrian President Bashar al-Assad's regime, but jihadist groups Jabhat Fateh Al-Sham and Jund al-Aqsa are active in the area, according to the Institute for the Study of War.
Wounded civilians attacked again
Government warplanes have targeted civilian ares such as hospitals, markets and mosques for several days, an Aleppo Media Center activist told CNN.
"Indiscriminate bombing and shelling continues in a shocking and unrelenting manner, killing and maiming civilians, subjecting them to a level of savagery that no human should have to endure," United Nations aid chief Stephen O'Brien said Sunday.
Civilians wounded by attacks now face grave danger if they dare seek treatment at a hospital.
After the spate of recent hospital bombings, only about 30 doctors remain for about 300,000 people in eastern Aleppo, said Adham Sahloul, spokesman for the Syrian American Medical Society,
Adding to the catastrophe: Bombings have also destroyed water infrastructure, depriving many Syrians of clean water.
Regime makes key gains in Aleppo
The recent attacks on rebel-held parts of Aleppo marked some of the worst violence since the start of the Syrian civil war war in 2011.
The state-run Syrian Arab News Agency said the army took over Aleppo's al-Kindi Hospital, perched on a strategic hill in the northern Aleppo, and killed "many terrorists." State-run media often call rebels "terrorists."
The takeover of al-Kindi hospital and the surrounding area cuts off a major rebel supply route that connected Aleppo to northern towns and the Turkish border.
Ammar Abdullah, a photographer based in the suburbs of Aleppo, said the recent regime advances were very significant.
"The takeover will further choke off the already under-supplied eastern Aleppo," he said.
But Zakaria Malahfji of the Fastaqim Union rebel group in Aleppo said, "We are not thinking at all of leaving the city."
"We chose the path of revolution, and we will not surrender," he added. "In fact, there are residents that are starting to carry weapons and fight the regime. There is a state of people's resistance now in Aleppo."
An estimated 430,000 Syrians have been killed since the civil war broke out in 2011. What started as peaceful demonstrations led to a violent government crackdown and an armed uprising calling for an end to the Assad family's four-decade rule.
Since then, terror groups such as ISIS and Fatah Al-Sham
have taken advantage of country's instability.
On Monday, Fatah Al-Sham said one of its members, Sheikh Ahmed Salama, was killed in a US-led coalition airstrike.
Pentagon spokesman Jeff Davis did not comment specifically on Salama, but said, "We can confirm we targeted a prominent al-Qaeda member and are assessing the results of the operation at this time."
The Syrian civil war has also spawned an international refugee crisis, as millions of civilians have tried to escape the incessant bloodshed.