Philip Grant, Consul General of Ireland of the Western United States, left, and Berkeley Mayor Tom Bates, second from left, stand with Berkeley fire fighters before placing wreaths at the Library Gardens apartment complex. 

Flags on public buildings are flying at half mast today as a mark of respect to the six students who died in Berkeley California.

Seven Irish students are being treated in hospital after the balcony collapse - two are said to be in a critical condition.

Investigations are underway into what caused the fourth floor balcony to give way.

Juliette Gash reports;

Five of the students were on J1 visas, while the sixth, 22 year old Ashley Donohoe was an Irish-American living in the San Francisco Bay area.

21 year old Dubliners Eoghan Culligan, Lorcán Miller, Nick Shuster, Olivia Burke and Eimear Walsh also lost their lives.

Ashley Donohoe and Olivia Burke were cousins.

All of the students were attending a 21st birthday party at the apartment when the balcony collapsed.

Workers remove part of a balcony that collapsed at the Library Gardens apartment complex.

Investigations are continuing into what caused the balcony to collapse.

Gene St Onge is a structural engineer based in California.

He says the balcony - which was less than a decade old - should have been able to carry the weight;

Floral tributes are being laid outside the complex where the six students lost their lives.

Women embrace after leaving flowers at the site of the balcony collapse.

Meanwhile, at home, books of condolence are being opened across the country.

University College Dublin, where Eimear Walsh, Niccolai (Nick) Schuster and Lorcán Miller were students, has opened up an online book.