The bombing of the theater became world news and it was long uncertain what had happened.
According to Mariupol's mayor, more than 1,000 people were in the building when it was attacked.
Ukrainian authorities have claimed that about 300 people lost their lives in the attack.
Responsibility for the act has been placed on Russia, which has denied involvement.
Now, more than a month after the incident, the news agency AP has published its own review of what actually happened, with testimonies from 23 survivors, photos and information about the building itself.
How they went can be read here.
The article states that at least 600 people died in and outside the theater, but with the firecracker that it is currently impossible to determine exactly how many died.
Witness: Bodies everywhere
One of those AP spoke to is Oksana Syomina, who is said to have been in the building with her husband when it met.
She describes a complete chaos, dust and blood.
Bodies were everywhere - adults and children.
Relatives stumbled around trying to find their loved ones.
- All these people are still under the racial masses.
No one has dug them up.
It is a large mass grave, she tells the news agency.
Several witnesses tell AP that the congestion at the theater was great.
Many who tried to get out were crushed.
36-year-old Dmitriy Yurin was one of those who came to the scene to help.
The shock wave after the attack threw him to the ground, but he got up and started digging people out of the building.
- I looked at my arms, they were covered in blood up to the elbows.
I was in shock, he says.
Important gathering place
Before the theater met, it had served as a central shelter for the people of the area.
The theater's employees had therefore written "children" in large white letters on the ground both in front of and behind the building to prevent attacks.
Mariupol, ravaged by violent fighting, was and still is largely without water and electricity.
In the theater, however, there was this, which is why many people went there, not only for necessities but also for information.
- We were immediately offered a cup of tea.
You have to understand, we had barely drunk or eaten in six days, everyone was so happy about the hot tea, says Galina Kutnyakova, who came to the theater just before the attack.
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The devastation in Mariupol is very great.
To the left is a picture from inside the theater that was bombed with hundreds of civilian casualties as a result, according to Ukrainian authorities.
Photo: Reuters