Video from the ground in central Gaza shows the aftermath of the destruction of a mosque and adjacent houses in the Al-Nuseirat refugee camp on Sunday.
The video, obtained by CNN from a Gaza-based journalist, shows a large amount of destruction at the site of an airstrike at Bilal Bin Rabbah mosque and people searching through the rubble to look for survivors.
According to medical sources at Al-Aqsa Martyrs Hospital in the nearby city of Deir Al-Balah, Gaza, an Israeli strike hit the mosque, killing 13 people and leaving "dozens" of other people injured.
CNN cannot independently verify the number of casualties.
Medical sources added that the victims were from several families who were taking shelter in houses around the site of the mosque after they were displaced from northern Gaza. The mosque in Al-Nuseirat is south of Wadi Gaza.
Additional footage that CNN obtained from the journalist on the ground shows people praying over several bodies that are wrapped in shrouds outside of Al-Aqsa Martyrs Hospital, as well as some of the victims' funerals.
"We were in 'Block C' of Al-Nuseirat. We were sleeping in God's grace, and we woke up to see everything coming down on us -- martyrs and injured and the entire house all on top of us, as you can see. My mother and sister died," said one of the survivors, Issa al-Ahmad, in an interview.
"There were no warnings. It was a strong airstrike. The people [nearby] pulled us from underneath the rubble."
Another survivor, Mohammad Ahmad, said in an interview that people from at least three families staying next to the mosque in "Block C" of the camp were killed.
"We were sleeping and all of sudden the glass and rubble were on top of us from every hole, we were terrified we started pulling the children outside," said Ahmad, adding that several children died in the strike.
"There were no warnings at all... We didn’t know exactly where the hit was, we started running to get our children out."
"Where are we supposed to go," added Ahmad, sitting on top of the rubble of his house.
CNN has reached out to the IDF for comment.
In a statement earlier on Sunday, the Israel Defense Forces (IDF) said it struck more than 450 targets in the past day, including command centers, observation posts, and missile launch sites, as Israel continues to expand its ground incursion into Gaza.
One video segment the IDF released along with its statement appears to show a missile hitting a building next to a mosque. It is not clear if that is the Bilal Ben Rabbah mosque.