RIO DE JANEIRO, Brazil -- Striking construction workers and security personnel clashed Monday at Rio de Janeiro's Olympic Park, the main cluster of venues under construction for the 2016 Summer Games.
Rio Mais, the consortium building the Olympic venues, confirmed that random gunshots were fired as workers and security confronted each other. There were no reports of injuries at the venue cluster, which is located 25 kilometres (15 miles) west of central Rio.
The work stoppage involving more than 2,000 workers began Thursday, and Rio Mais said it was unclear when work would resume.
"We are worried by the fact we are losing time," said Mario Andrada, spokesman for the Rio Olympic organizing committee. "Beyond that, there is catch-up to do and we will have to move faster to make up whatever time we've lost."
Andrada said he didn't have any details about the gunfire.
"Gunshots and violence worry us," he added. "But right now we don't know where this came from."
The labour dispute centres around which union represents the construction workers, and also involves benefits and working conditions.
Workers also went on strike Monday in central Rio de Janeiro at the stadium that will be used for track and field at the 2016 Olympics. The Joao Havelange Olympic Stadium, known in Rio as the Engenhao, has been closed since last year to fix structural problems with the roof.
The strikes are sure to capture the attention of the International Olympic Committee executive board, which is meeting this week in the Turkish Mediterranean resort of Belek.
A team of IOC inspectors visiting Rio almost three weeks ago, headed by Olympic hurdle champion Nawal El Moutawakel, said the games faced "challenging deadlines."
IOC President Thomas Bach has repeated often that Rio "doesn't have a day to lose," and some fear it could face chronic delays similar to those hitting the upcoming World Cup, which begins in two months.
The strike adds to a growing list of problems confronting Rio organizers with the games just over two years away.
Construction on the second largest cluster of venues in northern Rio de Janeiro, in an area called Deodoro, has yet to begin. Work on the Olympic golf course has also been delayed.
Severe water pollution in Rio's Guanabara Bay, the venue for Olympic sailing, is a growing concern with a test event scheduled there in August. IOC officials have said they will not risk the athletes' health if the water is unsafe.
Many of the delays are rooted in disputes among Brazil's three levels of government over who pays for what. Most estimates suggest Brazil will spend about $15 billion on the Olympics, a mix of public and private money.