A sixth person has died after a balcony crammed with people celebrating a 21st birthday collapsed at a housing complex in California.

Further details have not been released about the latest death.

Seven others are seriously injured after the fourth-floor balcony fell in the college town of Berkeley.

At leas five of the dead are students from Ireland who were in the US on work visas.

Usit Ireland, a Dublin-based organisation that helps Irish students enter the United States on exchange visas, says it is working with government officials in Ireland who have set up a special crisis centre to deal with the tragedy.

Building inspectors have barred people from using the remaining balconies in the complex.

Berkeley police spokesman Byron White said authorities want to inspect the remaining balconies for safety.

The apartment complex is a popular residence for University of California, Berkeley students. The building is near the university campus.

Irish Prime Minister Enda Kenny said police told him there were 13 people on the balcony when it collapsed.

Five people were killed and eight seriously injured Tuesday when the accident occurred during a 21st birthday party.

Two Irish students asleep in the building said they heard a bang as the balcony collapsed.

"I walked out and I saw rubble on the street and a bunch of Irish students crying," said Mark Neville, who has been in the US for three weeks under the J-1 visa programme.

"I just heard a bang and a lot of shouting," added 21-year-old Dan Sullivan.

Police say they received a noise complaint about a loud party about an hour before the balcony collapsed.

Officer Byron White, a spokesman for the Berkeley Police Department, said officers had not yet responded to the complaint before the collapse at 12.41am local time.