Two people have died in an accident at the stadium in Brazil that will host the opening ceremony of the 2014 World Cup finals.
The crane fell on top of a metal structure, destroying part of a facade at the Arena Corinthians in Sao Paulo.
Brazilian police said two people had been killed in Wednesday's accident. The crane operator was taken to hospital, but was later released.
Most of the workers are believed to have been away on their lunch breaks at the time.
Odebrecht Infrastructure, the company building the stadium, told the BBC the accident happened shortly before 1pm local time.
It said the crane that hoisted the last module of the structure of the metal roof collapsed, causing part of the circulation area of the east building to fall.
The company stressed that the structure of the stadium was not damaged.
The arena was due to be completed at the end of December to meet a FIFA deadline.
TV footage showed the huge metal structure buckled on top of the stadium, which is also known as Itaquerao.
Corinthians, the club that will move into the new stadium, said in a short statement that it deeply regretted the accident. Sepp Blatter, president of football's world governing body FIFA, said he was "deeply saddened by the tragic deaths".
This is the third fatal accident in World Cup stadiums in Brazil, with two other construction workers killed over the past two years.
Brazil has admitted it is struggling to have all 12 venues ready.