BERKELEY, Calif. — Hundreds attended a Mass Wednesday for victims of a deadly Berkeley balcony collapse, with the Catholic priest calling on people to offer support for the families of the six young people killed and the seven injured.

Earlier Wednesday, Berkeley Mayor Tom Bates said the collapse appears to have been caused by rotted wooden beams.

The crowded fifth-floor balcony broke off an apartment building during a 21st-birthday party early Tuesday held by visiting Irish college students, dumping 13 people 50 feet onto the pavement.