Family members of the six Irish students tragically killed in California balcony collapse on Tuesday have begun to arrive in the US.

Niccolai Schuster (21), Eoghan Culligan (21), Eimear Walsh (21), Olivia Burke (21) and Lorcan Miller (21) were spending the summer in America on a J1 summer visa. A sixth victim, Ashley Donohoe (22), had dual Irish-American citizenship and lived in the Bay Area of San Francisco. She was a cousin to Olivia Burke.

Seven others were injured in the accident, with two remaining in a critical condition.

From late Tuesday night and into Wednesday morning, family members of those killed and injured in the horrific incident have begun to arrive on America's West Coast.

At home, representatives from UCD have opened an online Book of Condolence through the college website. The college is also offering counselling and student support services to those affected. A Book of Condolence is also due to open at Dublin’s Mansion House on Thursday, while the Tricolour will be flown at half-mast at Government Buildings today in a mark of respect.

In Berkeley, locals and fellow Irish visitors continue to visit the scene of the accident, where the young pals were celebrating a 21st birthday party.

Fellow students left flags, flowers and other tokens to pay tribute to the dead.

Philip Grant, Consul General of Ireland to the Western United States, placed an Irish flag on two wreaths left at the scene.

Representatives from Aer Lingus said the airline company was "assisting family members in every way possible".

The cause of the collapse is not yet clear.