It was shortly after 1.30am when James Mullaney was abruptly awoken to a riot of noise "ringing out" through the Library Gardens apartment complex.
About 50 minutes earlier a balcony on the top floor had detached from the wall, sending unsuspecting Irish J1 students tumbling to the street.
"The noise was unbelievable," said the 20-year-old Laois native.
"I was fast asleep when my housemates ran into my room to tell me to check out what was happening outside. I looked out the window and there was a sea of fire trucks, ambulances and police cars.
"They were everywhere we looked. We had no idea what was going on. My friends decided to go downstairs where they saw people crying uncontrollably.
"But due to the location of our apartment, we couldn't see the debris and bodies on the ground. While we knew something serious had happened, we decided to leave it until the morning. We had no idea of the extent of what had taken place."
Meanwhile, tree branches, pieces of concrete and other debris littered the sidewalk outside the building, as a grim testament to the tragedy.
"We saw all that rubble on the footpath when we walked outside this morning. It was chilling. The whole area had been cordoned off by the police.
"Soon there were hundreds of reporters running around trying to find out more information."
He described the apartment complex balconies as "small enough" and said that they might only hold around six people.
Speaking to the Irish Independent, he described accommodation at the Library Gardens Apartments as "top notch", adding that the location is a "well-to-do area".
On its website, the complex, with manicured lawns, is described as the "premiere choice for convenient Berkeley apartments".
Units rent for $2,150 to $4,000 a month.
"Berkeley is very safe and one of the nicest areas in San Francisco," James said. "The majority of tenants in this block are either Asian or Irish."
James had arrived at the 177-unit complex just three weeks ago with three friends from Galway. He said the tragedy had cast a dark shadow over their American trip. "Everyone is just stunned," he added.
Meanwhile, Silvia Biswas who lives on the third floor of Library Gardens, described the collapse of the balcony as like "a really big earthquake which left the complex shaking".
She called emergency services immediately when she looked out and saw bodies on the ground.
"When the balcony was falling down, we thought it was an earthquake, and a really big earthquake. It was shaking my window. It was kind of like the building itself was falling down," she said.