"I wasn't aware of the magnitude of what had happened though."
O'Dea left the stadium, following instructions to use specific exits, and headed for a meeting place arranged with friends.
"As we were walking there, however, all of a sudden crowds of people in that direction started running towards us, some screaming. We had no idea what what happening but Maddie grabbed my arm and we turned around and just started running.
"Even now I still don't know what happened to cause that. It could have just been police blocking off that area and telling people to go in the other direction quickly and some people ran, causing a chain reaction in the crowd? Regardless, it was very scary."
O'Dea said the internet had crashed so it was impossible to check for news.
"We did not want to risk sticking around in case there was a bomber or shooter there. We didn't know where to go, though, and didn't know if the metros were safe or not.
"In the end we walked around for maybe an hour and also contacted our families to let them know we were safe when the internet network was working again. Managed to flag down an unoccupied taxi and it took us home."
At that point, her phone was flooded with delayed messages and calls from family and friends.
"Mum sounded very calm on the phone, which I am sure was for my benefit at the time, in order to make sure I didn't freak out. Have received several phone calls from her and Dad since then, checking in."
O'Dea is on an exchange from Victoria University to the Paris Institute of Political Studies, known as Sciences Po.