YEREVAN, Armenia (AP) — Rockets hit a hospital and residential areas Wednesday amid deadly fighting between Armenian and Azerbaijani forces over the separatist region of Nagorno-Karabakh that has raged for more than a month despite a U.S.-brokered cease-fire.

In Nagorno-Karabakh, an Azerbaijani rocket hit a maternity hospital but inflicted no casualties. Azerbaijani authorities denied responsibility and in turn accused Armenia of launching a rocket strike on the town of Barda that killed more than 20 civilians and wounded over 70. Armenia rejected the accusations.

Nagorno-Karabakh officials said Azerbaijani forces hit Stepanakert, the region’s capital, and the nearby town of Shushi with Smerch long-range multiple rocket systems, a devastating Soviet-designed weapon intended to ravage wide areas with explosives and cluster munitions. One civilian was killed in Shushi and two more were wounded, officials said.

There were no patients or medical personnel in the maternity hospital in Stepanakert at the moment of the strike, which also damaged adjacent premises of a sprawling medical center filled with patients.

Mger Musailyan, the center’s chief doctor, denounced the attack as “inhumane,” noting that the medical center is treating COVID-19 patients among others. The region has seen a spike in infections amid the fighting that has diverted scarce medical resources to treat the wounded.

“This is absurd to attack a hospital. It’s prohibited in the whole world,” Musailyan said.

Inna Gasparyan, the chief nurse, said the coronavirus patients are helpless. “Those patients who are here, they are all on breathing machines, they are very sick and they cannot be evacuated to the basement,” she said.

The Azerbaijani Defense Ministry denied hitting the maternity hospital and targeting other civilian areas and in turn accused Armenian forces of using the Smerch multiple rocket system to fire at the Azerbaijani towns of Terter and Barda. The strike on Barda killed at least 21 civilians, including children, and wounded more than 70, Azerbaijani officials said.

Armenian Defense Ministry spokeswoman Shushan Stepanian called accusations of striking Barda “groundless and false.”

Azerbaijani President Ilham Aliyev promised on Twitter a “befitting response” for the strike.

Nagorno-Karabakh lies within Azerbaijan but has been under the control of ethnic Armenian forces backed by Armenia since a war there ended in 1994. By then, Armenian forces not only held Nagorno-Karabakh itself but also captured substantial areas outside the territory’s borders.

The latest fighting, which began Sept. 27, has involved heavy artillery, rockets and drones, in the largest escalation of hostilities over the separatist region in the quarter-century since the war ended. Hundreds, and possibly thousands of people, have been killed in the latest fighting.

The hostilities have raged for over a month despite international calls for peace and three attempts at establishing a cease-fire. The latest U.S.-brokered truce frayed immediately after it took effect Monday, just like two previous cease-fires negotiated by Russia. The warring sides blamed each other for violations.