Rescue efforts are underway after a theater in Mariupol that was serving as a Ukrainian civilian shelter was destroyed by a Russian airstrike.

Following the attack on Wednesday night (March 16), rescue workers said “there are survivors” in the building’s rubble while continuing efforts to find and evacuate civilians on Thursday morning (March 17).

According to The Kyiv Independent, 130 people have been rescued from the building’s ruins so far.

“130 survivors saved so far from ruins of Mariupol Drama Theater, which Russians hit with [a] massive bomb on March 16,” the outlet wrote on Twitter Thursday. “The theater was known to house hundreds of women and children. Its bomb shelter reportedly survived the attack. The rescue efforts continue.”

According to Ukrainian authorities, the three-story theater had served as a shelter for hundreds of people since Russia launched its attack on Ukraine, including children and elderly and disabled people.

The Mariupol City Council said Russian forces “purposefully and cynically destroyed the Drama Theater in the heart of Mariupol… where hundreds of peaceful Mariupol residents were hiding.”

According to CNN, satellite images of the theater showed civilians had written the word “children” on the sides of the building, indicating there were children sheltering there, before it was bombed.

Speaking to Reuters on Thursday, Petro Andrushchenko, an adviser to the city’s mayor; said, “The bomb shelter held. Now the rubble is being cleared. There are survivors. We don’t know about the [number of] victims yet.”

Mariupol has been hit hard by Russian forces. The city’s mayor told CNN on Tuesday (March 15) that they counted 22 Russian aircrafts “which were bombing our city, and at least 100 bombs.”

Ukrainian officials say at least 2,500 civilians have died in the city and many more are unable to leave. According to CNN, civilians who were able to flee have described the city’s conditions as “unbearable,” as residents are currently without electricity, water and heat.